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A093302
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a(n) = (a(n-1)+(2n-1))*(2n) with a(0) = 0.
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3
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0, 2, 20, 150, 1256, 12650, 151932, 2127230, 34035920, 612646866, 12252937700, 269564629862, 6469551117240, 168208329048890, 4709833213369676, 141294996401091150, 4521439884834917792, 153728956084387206050
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) = 2 * floor(e^(1/2) * n! * 2^n) - 2n - 2.
E.g.f.: (2x+4x^2)/(1-2x) * exp(x).
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MATHEMATICA
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RecurrenceTable[{a[0]==0, a[n]==(a[n-1]+2n-1)2n}, a, {n, 20}] (* Harvey P. Dale, May 20 2014 *)
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PROG
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(PARI) a(n)=2*floor(exp(1/2)*n!*2^n)-2*n-2
(PARI) x='x+O('x^99); concat(0, Vec(serlaplace((2*x+4*x^2)/(1-2*x)*exp(x)))) \\ Altug Alkan, Aug 01 2018
(PARI) a=vector(99); a[1]=2; for(n=2, #a, a[n] = 2*(a[n-1]+2*n-1)*n); concat(0, a) \\ Altug Alkan, Aug 01 2018
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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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Emrehan Halici (emrehan(AT)halici.com.tr), Apr 24 2004
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EXTENSIONS
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STATUS
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approved
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