A272503 Number of n-letter strings over a ten letter alphabet where no letter appears exactly five times.

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)).

Links

Table of n, a(n) for n=0..20.

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

Cf. A265325, A272501, A272502.

Sequence in context: A232660 A052211 A136845 * A136837 A136854 A029778

Adjacent sequences: A272500 A272501 A272502 * A272504 A272505 A272506

Keyword

base,nonn

Author

Marko Riedel, May 01 2016

Status

approved