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URL: https://oeis.org/A035279

⇱ A035279 - OEIS

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A035279
One tenth of deca-factorial numbers.
11
1, 20, 600, 24000, 1200000, 72000000, 5040000000, 403200000000, 36288000000000, 3628800000000000, 399168000000000000, 47900160000000000000, 6227020800000000000000, 871782912000000000000000, 130767436800000000000000000, 20922789888000000000000000000
OFFSET
1,2
COMMENTS
E.g.f. is g.f. for A011557(n-1) (powers of ten).
FORMULA
10*a(n) = (10*n)(!^10) = Product_{j=1..n} 10*j = 10^n*n!.
E.g.f.: (-1 + (1-10*x)^(-1))/10.
From Amiram Eldar, Jan 08 2022: (Start)
Sum_{n>=1} 1/a(n) = 10*(exp(1/10)-1).
Sum_{n>=1} (-1)^(n+1)/a(n) = 10*(1-exp(-1/10)). (End)
MAPLE
seq(10^(n-1)*n!, n=1..20); # G. C. Greubel, Nov 11 2019
MATHEMATICA
Table[10^(n-1)*n!, {n, 20}] (* G. C. Greubel, Nov 11 2019 *)
PROG
(PARI) vector(20, n, 10^(n-1)*n! ) \\ G. C. Greubel, Nov 11 2019
(Magma) [10^(n-1)*Factorial(n): n in [1..20]]; // G. C. Greubel, Nov 11 2019
(SageMath) [10^(n-1)*factorial(n) for n in (1..20)] # G. C. Greubel, Nov 11 2019
(GAP) List([1..20], n-> 10^(n-1)*Factorial(n) ); # G. C. Greubel, Nov 11 2019
CROSSREFS
Sequence in context: A184123 A027407 A116218 * A015268 A202577 A059420
KEYWORD
easy,nonn
STATUS
approved