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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 (list; graph; refs; listen; history; text; internal format)
 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 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

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Last modified September 22 06:01 EDT 2021. Contains 347605 sequences. (Running on oeis4.)