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A092634
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a(n) = 1 - Sum_{k=2..n} k*k!.
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1
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-3, -21, -117, -717, -5037, -40317, -362877, -3628797, -39916797, -479001597, -6227020797, -87178291197, -1307674367997, -20922789887997, -355687428095997, -6402373705727997, -121645100408831997, -2432902008176639997
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OFFSET
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2,1
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REFERENCES
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Appeared in University of Texas Interscholastic League High School Number Sense District Test, 2004.
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LINKS
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FORMULA
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Conjecture: a(n) +(-n-3)*a(n-1) +(2*n+1)*a(n-2) +(-n+1)*a(n-3)=0. - R. J. Mathar, Sep 27 2014
E.g.f.: 3*exp(x) - (3 - 3*x + x^3)/(1-x)^2. (End)
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MAPLE
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MATHEMATICA
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Table[i; 1 - Sum[n n!, {n, 2, i}], {i, 2, 20}]
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PROG
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(PARI) a(n) = 1 - sum(k=2, n, k*k!); \\ Michel Marcus, Jun 07 2020
(Sage) [3-factorial(n+1) for n in (2..20)] # G. C. Greubel, Jun 07 2020
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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Doug Ray (draymath(AT)iastate.edu), Apr 11 2004
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STATUS
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approved
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