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 A265325 Number of n-digit decimal numbers with leading zeros allowed where no digit appears exactly twice. 3
 10, 90, 730, 5410, 37900, 264250, 1908910, 14322520, 110305720, 875799550, 7203731050, 60866700940, 527138423380, 4696469283970, 42797376850150, 397903278667600, 3783002076771760, 36604891556846470, 360117919584474850, 3603555076712108500 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Math Stackexchange, Marko Riedel et al., N digit numbers with no digit appearing exactly twice. FORMULA E.g.f.: Sum_{q=1..N} C(10,q)*(exp(z)-z^2/2-1)^q. E.g.f.: (exp(z)-z^2/2)^10. EXAMPLE Computing the value for n=1 the ten one-digit numbers 0-9 all qualify. Computing the value for n=2 of two-digit numbers 00-99 all qualify except those consisting of a double digit (00, 11, ..., 99). MAPLE STNE2 := (n, k)->n!*coeftayl((exp(z)-z^2/2-1)^k/k!, z=0, n); a(N) := N -> add(combinat:-binomial(10, q)*STNE2(N, q)*q!, q = 1 .. N) CROSSREFS Cf. A272501, A272502, A272503. Sequence in context: A319893 A319874 A159733 * A038726 A009454 A231530 Adjacent sequences:  A265322 A265323 A265324 * A265326 A265327 A265328 KEYWORD nonn,base AUTHOR Marko Riedel, Apr 30 2016 STATUS approved

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Last modified August 20 20:50 EDT 2019. Contains 326155 sequences. (Running on oeis4.)