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A126643 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, at least one of digits 5,6 and at least one of digits 7,8,9. 3
6, 34, 180, 886, 4116, 18334, 79260, 335446, 1398276, 5765134, 23581740, 95900806, 388345236, 1567647934, 6313474620, 25382710966, 101917608996, 408831386734, 1638809709900, 6565693949926, 26294146373556, 105270707701534, 421365218399580 (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) = 6*4^n-9*3^n+5*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.: -2*x*(12*x^3-25*x^2+13*x-3) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)). - Colin Barker, Feb 22 2015

MAPLE

f:=n->6*4^n-9*3^n+5*2^n-1;

PROG

(PARI) Vec(-2*x*(12*x^3-25*x^2+13*x-3) / ((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: A198765 A274405 A144142 * A320745 A084775 A327740

Adjacent sequences: A126640 A126641 A126642 * A126644 A126645 A126646

KEYWORD

nonn,base,easy

AUTHOR

Aleksandar M. Janjic and Milan Janjic, Feb 08 2007

STATUS

approved

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Last modified January 29 08:01 EST 2023. Contains 359915 sequences. (Running on oeis4.)