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A272503
Number of n-letter strings over a ten letter alphabet where no letter appears exactly five times.
3
1, 10, 100, 1000, 10000, 99990, 999460, 9982990, 99591760, 991733140, 9851207860, 97545740500, 962166785680, 9447649239610, 92290336898860, 896407655754610, 8653070630861920, 82985161693086280, 790512637315007440, 7479643461956322760, 70304610246340134880
OFFSET
0,2
COMMENTS
Species is SEQ_10(SET_(!=5)(Z)).
FORMULA
E.g.f.: (exp(z)-z^5/5!)^10.
EXAMPLE
a(5) = 10^5-10 because all 5-letter strings qualify except the strings containing only one type of letter.
MAPLE
a:= n->n!*coeftayl((exp(z)-z^5/5!)^10, z=0, n): seq(a(n), n=0..20);
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Marko Riedel, May 01 2016
STATUS
approved