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Search: id:A122017
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| A122017 |
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a(n) = if n even then a(n - 1) - (n - 1)*a(n - 2) otherwise 2*(a(n - 1) + (n - 1)*a(n - 2])). |
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1
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| 1, 2, 1, 10, 7, 94, 59, 1246, 833, 21602, 14105, 460250, 305095, 11656190, 7689955, 341753230, 226403905, 11388911170, 7540044785, 425080891690, 281820040775, 17566875749150, 11648654892875, 796239842748350, 528320780212225
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OFFSET
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1,2
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MATHEMATICA
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a[0] = 1; a[1] = 2; a[n_] := a[n] = If[Mod[n, 2] == 0, a[n - 1] - (n - 1)*a[n - 2], 2*(a[n - 1] + (n - 1)*a[n - 2])] b = Table[a[n], {n, 0, 30}]
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CROSSREFS
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Cf. A000898, A121966.
Sequence in context: A004747 A155810 A081099 this_sequence A136233 A113088 A060694
Adjacent sequences: A122014 A122015 A122016 this_sequence A122018 A122019 A122020
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KEYWORD
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nonn
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AUTHOR
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Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 11 2006
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Sep 13 2006
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