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A125904
a(n) is the number of nonnegative integers k less than 10^n such that the decimal representation of k lacks at least one of the digits 1,2,3,4 and at least one of the digits 5,6,7,8,9.
19
10, 100, 1000, 9976, 98920, 971440, 9420400, 90005176, 846101080, 7822770880, 71163913600, 637585923976, 5633160763240, 49148451899920, 424055315011600, 3623013325068376, 30689130457473400, 258015134469182560, 2155143129458730400
OFFSET
1,1
LINKS
FORMULA
a(n) = 20*8^n-70*7^n+120*6^n-125*5^n+84*4^n-36*3^n+9*2^n-1.
G.f.: -2*x*(20160*x^7 -54792*x^6 +53362*x^5 -28337*x^4 +8392*x^3 -1430*x^2 +130*x -5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)*(8*x -1)). - Colin Barker, Feb 23 2015
MAPLE
f:=n->20*8^n-70*7^n+120*6^n-125*5^n+84*4^n-36*3^n+9*2^n-1;
PROG
(PARI) vector(100, n, 20*8^n-70*7^n+120*6^n-125*5^n+84*4^n-36*3^n+9*2^n-1) \\ Colin Barker, Feb 23 2015
CROSSREFS
Cf. A125630.
Sequence in context: A358442 A136877 A257969 * A272502 A355894 A276596
KEYWORD
nonn,base,easy
AUTHOR
Aleksandar M. Janjic and Milan Janjic, Feb 03 2007
STATUS
approved