OFFSET
0,2
COMMENTS
Species is SEQ_10(SET_(!=5)(Z)).
LINKS
Math Stackexchange, Marko Riedel et al., N digit numbers with no digit appearing exactly twice.
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