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A125948
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 digits 1,2,3, at least one of digits 4,5,6 and at least one of digits 7,8,9.
19
10, 100, 982, 9388, 86950, 778780, 6748822, 56713708, 463661830, 3700940860, 28941318262, 222422713228, 1684544507110, 12602134130140, 93308618633302, 684912371803948, 4990975002030790, 36147245625290620, 260449744313893942
OFFSET
1,1
FORMULA
a(n) = 27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1.
G.f.: -2*x*(2520*x^6 -6012*x^5 +5990*x^4 -2754*x^3 +701*x^2 -90*x +5) / ((x -1)*(2*x -1)*(3*x -1)*(4*x -1)*(5*x -1)*(6*x -1)*(7*x -1)). - Colin Barker, Feb 23 2015
MAPLE
f:=n->27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1;
MATHEMATICA
Table[27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1, {n, 19}] (* James C. McMahon, Dec 23 2024 *)
PROG
(PARI) vector(100, n, 27*7^n-81*6^n+108*5^n-81*4^n+36*3^n-9*2^n+1) \\ Colin Barker, Feb 23 2015
CROSSREFS
Cf. A125630.
Sequence in context: A231163 A136858 A334612 * A121084 A272501 A171284
KEYWORD
nonn,base,easy
AUTHOR
Aleksandar M. Janjic and Milan Janjic, Feb 04 2007
STATUS
approved