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A011266
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a(n) = 2^(n*(n-1)/2)*n!.
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13
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1, 1, 4, 48, 1536, 122880, 23592960, 10569646080, 10823317585920, 24936923717959680, 127677049435953561600, 1438154284846580917862400, 35344079704389572637386342400, 1882001556099335963795547960115200, 215842994465920643015783804449692057600
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OFFSET
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0,3
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COMMENTS
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Let A = the sum of the n-th powers of the first 2^{n-1} terms of A001969, and similarly let B = the sum of the n-th powers of the first 2^{n-1} terms of A000069. Then a(n) = |A-B|. - Jeffrey Shallit, Nov 29 2019
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LINKS
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FORMULA
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a(n) = a(n-1)*n*2^(n-1), a(0) = 1.
G.f. satisfies A(x) = 1 + x * (x * A(2*x))'. (End)
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MAPLE
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a:= n-> 2^(n*(n-1)/2)*n!:
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MATHEMATICA
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Table[2^((n(n-1))/2) n!, {n, 0, 20}] (* Harvey P. Dale, Dec 16 2012 *)
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PROG
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(PARI) a(n) = n! << binomial(n, 2); \\ Kevin Ryde, Mar 10 2022
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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