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A035279
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One tenth of deca-factorial numbers.
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11
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1, 20, 600, 24000, 1200000, 72000000, 5040000000, 403200000000, 36288000000000, 3628800000000000, 399168000000000000, 47900160000000000000, 6227020800000000000000, 871782912000000000000000, 130767436800000000000000000, 20922789888000000000000000000
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OFFSET
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1,2
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COMMENTS
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E.g.f. is g.f. for A011557(n-1) (powers of ten).
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LINKS
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FORMULA
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10*a(n) = (10*n)(!^10) = Product_{j=1..n} 10*j = 10^n*n!.
E.g.f.: (-1 + (1-10*x)^(-1))/10.
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)
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MAPLE
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MATHEMATICA
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PROG
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(Magma) [10^(n-1)*Factorial(n): n in [1..20]]; // G. C. Greubel, Nov 11 2019
(Sage) [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
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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