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A126640
a(n) is the number of integers k less than 10^n such that the decimal representation of k lacks the digit 1 and 2, at least one of digits 3,4, at least one of digits 5,6 and at least one of digits 7,8,9.
3
8, 60, 422, 2784, 17318, 102600, 584942, 3237504, 17516438, 93136440, 488625662, 2537103024, 13068059558, 66890498280, 340713533582, 1728792901344, 8745409322678, 44134458900120, 222306845468702, 1118087142184464, 5616691514201798, 28188613237893960
OFFSET
1,1
FORMULA
a(n) = 12*5^n-24*4^n+19*3^n-7*2^n+1.
G.f.: -2*x*(60*x^4-123*x^3+101*x^2-30*x+4) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)). - Colin Barker, Feb 22 2015
MAPLE
f:=n->12*5^n-24*4^n+19*3^n-7*2^n+1;
PROG
(PARI) Vec(-2*x*(60*x^4-123*x^3+101*x^2-30*x+4) / ((x-1)*(2*x-1)*(3*x-1)*(4*x-1)*(5*x-1)) + O(x^100)) \\ Colin Barker, Feb 22 2015
KEYWORD
nonn,base,easy
AUTHOR
Aleksandar M. Janjic and Milan Janjic, Feb 08 2007
STATUS
approved