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 A126642 a(n) is the number of integers k less than 10^n such that the decimal representation of k lacks the digits 1,2,3,4 and 5 and at least one of digits 6,7,8,9. 3
 5, 25, 125, 601, 2765, 12265, 52925, 223801, 932525, 3844105, 15722525, 63936601, 258902285, 1045109545, 4209004925, 16921851001, 67945160045, 272554432585, 1092540156125, 4377129999001, 17529432313805, 70180474597225, 280910151192125 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Colin Barker, Table of n, a(n) for n = 1..1000 Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets Index entries for linear recurrences with constant coefficients, signature (10,-35,50,-24). FORMULA a(n) = 4*4^n-6*3^n+4*2^n-1. a(n) = 10*a(n-1)-35*a(n-2)+50*a(n-3)-24*a(n-4). - Colin Barker, Feb 22 2015 G.f.: -x*(24*x^3-50*x^2+25*x-5) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)). - Colin Barker, Feb 22 2015 MAPLE f:=n->4*4^n-6*3^n+4*2^n-1; PROG (PARI) Vec(-x*(24*x^3-50*x^2+25*x-5) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)) + O(x^100)) \\ Colin Barker, Feb 22 2015 CROSSREFS Cf. A125630, A125948, A125947, A125946, A125945, A125940, A125909, A125908, A125880, A125897, A125904, A125858. Sequence in context: A366323 A267780 A228736 * A269615 A269579 A269431 Adjacent sequences: A126639 A126640 A126641 * A126643 A126644 A126645 KEYWORD nonn,base,easy AUTHOR Aleksandar M. Janjic and Milan Janjic, Feb 08 2007 STATUS approved

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Last modified March 3 00:46 EST 2024. Contains 370499 sequences. (Running on oeis4.)