Order = maximum 3 letters per decade

deleted request for file...

There only 7 ways to choose 5 numbers:

5 from a single decade
4 from one and 1 from a second
3 from one and 2 from a second
3 from one, 1 from a second, and 1 from a third
2 from one, 2 from a second, and 1 from a third
2 from one, 1 from a second, and 1 from a third, and 1 from a fourth
1 from each of 5

Your rule only excludes the first two ways, and includes 23,920,400 of the 24,040,016 combinations.

	A	B	C	D	E	F	G	H	I
1		(Not OK)	(Not OK)	(OK)	(OK)	(OK)	(OK)	(OK)
2	Decade	Choose	Choose	Choose	Choose	Choose	Choose	Choose
3	One decade	5	4	3	3	2	2	1
4	Another decade		1	2	1	2	1	1
5	Another decade				1	1	1	1
6	Another decade						1	1
7	Another decade							1
8
9	Ways to choose decades	8	28	28	56	56	70	56	B9: =COMBIN(8, COUNT(B3:B7))
10	Permutations of Counts w/in Decades	1	2	2	3	3	4	1	B10: {=FACT(COUNT(B3:B7)) / PRODUCT(FACT(COUNTIF(B3:B7, {1,2,3,4,5})))}
11	Ways to choose within decades	252	2,100	5,400	12,000	20,250	45,000	100,000	B11: {=PRODUCT(COMBIN(10, B3:B7))}
12	Combinations	2,016	117,600	302,400	2,016,000	3,402,000	12,600,000	5,600,000	B12: =PRODUCT(B9:B11)
13
14	Total Combinations							24,040,016	H14: =SUM(B12:H12)
15	Check that							24,040,016	H15: =COMBIN(80,5)
16	Total OK Combinations							23,920,400	H16: =SUM(D12:H12)

aaabb	aaccc	abbbc	abdeh	acdff	adggg	bbccc	bcccd	bdddf	bffhh	ccghh	cfffh	deggg
aaabc	aaccd	abbbd	abdff	acdfg	adggh	bbccd	bccce	bdddg	bfggg	cchhh	cffgg	deggh
aaabd	aacce	abbbe	abdfg	acdfh	adghh	bbcce	bcccf	bdddh	bfggh	cddde	cffgh	deghh
aaabe	aaccf	abbbf	abdfh	acdgg	adhhh	bbccf	bcccg	bddee	bfghh	cdddf	cffhh	dehhh
aaabf	aaccg	abbbg	abdgg	acdgh	aeeef	bbccg	bccch	bddef	bfhhh	cdddg	cfggg	dfffg
aaabg	aacch	abbbh	abdgh	acdhh	aeeeg	bbcch	bccdd	bddeg	bgggh	cdddh	cfggh	dfffh
aaabh	aacdd	abbcc	abdhh	aceee	aeeeh	bbcdd	bccde	bddeh	bgghh	cddee	cfghh	dffgg
aaacc	aacde	abbcd	abeee	aceef	aeeff	bbcde	bccdf	bddff	bghhh	cddef	cfhhh	dffgh
aaacd	aacdf	abbce	abeef	aceeg	aeefg	bbcdf	bccdg	bddfg	cccdd	cddeg	cgggh	dffhh
aaace	aacdg	abbcf	abeeg	aceeh	aeefh	bbcdg	bccdh	bddfh	cccde	cddeh	cgghh	dfggg
aaacf	aacdh	abbcg	abeeh	aceff	aeegg	bbcdh	bccee	bddgg	cccdf	cddff	cghhh	dfggh
aaacg	aacee	abbch	abeff	acefg	aeegh	bbcee	bccef	bddgh	cccdg	cddfg	dddee	dfghh
aaach	aacef	abbdd	abefg	acefh	aeehh	bbcef	bcceg	bddhh	cccdh	cddfh	dddef	dfhhh
aaadd	aaceg	abbde	abefh	acegg	aefff	bbceg	bcceh	bdeee	cccee	cddgg	dddeg	dgggh
aaade	aaceh	abbdf	abegg	acegh	aeffg	bbceh	bccff	bdeef	cccef	cddgh	dddeh	dgghh
aaadf	aacff	abbdg	abegh	acehh	aeffh	bbcff	bccfg	bdeeg	ccceg	cddhh	dddff	dghhh
aaadg	aacfg	abbdh	abehh	acfff	aefgg	bbcfg	bccfh	bdeeh	ccceh	cdeee	dddfg	eeeff
aaadh	aacfh	abbee	abfff	acffg	aefgh	bbcfh	bccgg	bdeff	cccff	cdeef	dddfh	eeefg
aaaee	aacgg	abbef	abffg	acffh	aefhh	bbcgg	bccgh	bdefg	cccfg	cdeeg	dddgg	eeefh
aaaef	aacgh	abbeg	abffh	acfgg	aeggg	bbcgh	bcchh	bdefh	cccfh	cdeeh	dddgh	eeegg
aaaeg	aachh	abbeh	abfgg	acfgh	aeggh	bbchh	bcddd	bdegg	cccgg	cdeff	dddhh	eeegh
aaaeh	aaddd	abbff	abfgh	acfhh	aeghh	bbddd	bcdde	bdegh	cccgh	cdefg	ddeee	eeehh
aaaff	aadde	abbfg	abfhh	acggg	aehhh	bbdde	bcddf	bdehh	ccchh	cdefh	ddeef	eefff
aaafg	aaddf	abbfh	abggg	acggh	afffg	bbddf	bcddg	bdfff	ccddd	cdegg	ddeeg	eeffg
aaafh	aaddg	abbgg	abggh	acghh	afffh	bbddg	bcddh	bdffg	ccdde	cdegh	ddeeh	eeffh
aaagg	aaddh	abbgh	abghh	achhh	affgg	bbddh	bcdee	bdffh	ccddf	cdehh	ddeff	eefgg
aaagh	aadee	abbhh	abhhh	addde	affgh	bbdee	bcdef	bdfgg	ccddg	cdfff	ddefg	eefgh
aaahh	aadef	abccc	acccd	adddf	affhh	bbdef	bcdeg	bdfgh	ccddh	cdffg	ddefh	eefhh
aabbb	aadeg	abccd	accce	adddg	afggg	bbdeg	bcdeh	bdfhh	ccdee	cdffh	ddegg	eeggg
aabbc	aadeh	abcce	acccf	adddh	afggh	bbdeh	bcdff	bdggg	ccdef	cdfgg	ddegh	eeggh
aabbd	aadff	abccf	acccg	addee	afghh	bbdff	bcdfg	bdggh	ccdeg	cdfgh	ddehh	eeghh
aabbe	aadfg	abccg	accch	addef	afhhh	bbdfg	bcdfh	bdghh	ccdeh	cdfhh	ddfff	eehhh
aabbf	aadfh	abcch	accdd	addeg	agggh	bbdfh	bcdgg	bdhhh	ccdff	cdggg	ddffg	efffg
aabbg	aadgg	abcdd	accde	addeh	agghh	bbdgg	bcdgh	beeef	ccdfg	cdggh	ddffh	efffh
aabbh	aadgh	abcde	accdf	addff	aghhh	bbdgh	bcdhh	beeeg	ccdfh	cdghh	ddfgg	effgg
aabcc	aadhh	abcdf	accdg	addfg	bbbcc	bbdhh	bceee	beeeh	ccdgg	cdhhh	ddfgh	effgh
aabcd	aaeee	abcdg	accdh	addfh	bbbcd	bbeee	bceef	beeff	ccdgh	ceeef	ddfhh	effhh
aabce	aaeef	abcdh	accee	addgg	bbbce	bbeef	bceeg	beefg	ccdhh	ceeeg	ddggg	efggg
aabcf	aaeeg	abcee	accef	addgh	bbbcf	bbeeg	bceeh	beefh	cceee	ceeeh	ddggh	efggh
aabcg	aaeeh	abcef	acceg	addhh	bbbcg	bbeeh	bceff	beegg	cceef	ceeff	ddghh	efghh
aabch	aaeff	abceg	acceh	adeee	bbbch	bbeff	bcefg	beegh	cceeg	ceefg	ddhhh	efhhh
aabdd	aaefg	abceh	accff	adeef	bbbdd	bbefg	bcefh	beehh	cceeh	ceefh	deeef	egggh
aabde	aaefh	abcff	accfg	adeeg	bbbde	bbefh	bcegg	befff	cceff	ceegg	deeeg	egghh
aabdf	aaegg	abcfg	accfh	adeeh	bbbdf	bbegg	bcegh	beffg	ccefg	ceegh	deeeh	eghhh
aabdg	aaegh	abcfh	accgg	adeff	bbbdg	bbegh	bcehh	beffh	ccefh	ceehh	deeff	fffgg
aabdh	aaehh	abcgg	accgh	adefg	bbbdh	bbehh	bcfff	befgg	ccegg	cefff	deefg	fffgh
aabee	aafff	abcgh	acchh	adefh	bbbee	bbfff	bcffg	befgh	ccegh	ceffg	deefh	fffhh
aabef	aaffg	abchh	acddd	adegg	bbbef	bbffg	bcffh	befhh	ccehh	ceffh	deegg	ffggg
aabeg	aaffh	abddd	acdde	adegh	bbbeg	bbffh	bcfgg	beggg	ccfff	cefgg	deegh	ffggh
aabeh	aafgg	abdde	acddf	adehh	bbbeh	bbfgg	bcfgh	beggh	ccffg	cefgh	deehh	ffghh
aabff	aafgh	abddf	acddg	adfff	bbbff	bbfgh	bcfhh	beghh	ccffh	cefhh	defff	ffhhh
aabfg	aafhh	abddg	acddh	adffg	bbbfg	bbfhh	bcggg	behhh	ccfgg	ceggg	deffg	fgggh
aabfh	aaggg	abddh	acdee	adffh	bbbfh	bbggg	bcggh	bfffg	ccfgh	ceggh	deffh	fgghh
aabgg	aaggh	abdee	acdef	adfgg	bbbgg	bbggh	bcghh	bfffh	ccfhh	ceghh	defgg	fghhh
aabgh	aaghh	abdef	acdeg	adfgh	bbbgh	bbghh	bchhh	bffgg	ccggg	cehhh	defgh	ggghh
aabhh	aahhh	abdeg	acdeh	adfhh	bbbhh	bbhhh	bddde	bffgh	ccggh	cfffg	defhh	gghhh

Maybe 3rd time's the charm