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A161557
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a(n) = (n+1)*A000521(n), n>(-1).
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1
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1, 744, 393768, 64481280, 3457199880, 101229281280, 1999215843600, 29764163100672, 357255952575480, 3613417979904000, 31764402297844200, 248241326405529600, 1754542937994231528, 11366078355915079680, 68208141565173995280
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OFFSET
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-1,2
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COMMENTS
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[Mathworld]: "Lehmer(1942) showed that (n+1)*C(n) == 0 mod 24 for n >= 1" Cf. A161395: (0, 31, 16407, 2686720, 144049995,...) = ((n+1)*A000521(n)) / 24.
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LINKS
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FORMULA
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EXAMPLE
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a(2) = 64481280 = 3*A000521(2) = 3*21493760; such that 64481280 == 0 mod 24, where 64481280 / 24 = 2686720 = A161395(2).
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MATHEMATICA
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a[n_] := With[{tau = Log[q]/(2 Pi I)}, SeriesCoefficient[Series[1728 *KleinInvariantJ[tau], {q, 0, n}], {q, 0, n}]]; Join[{1}, Table[(n + 1)*a[n], {n, 0, 50}]] (* G. C. Greubel, Feb 25 2017 *)
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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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