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Search: id:A122578
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| A122578 |
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A switch between two types of n level recursion: Even:a(n)=(n - 1)*a(n - 1) - a(n - 2) Odd:a(n)=a(n - 1) - (n - 2)*a(n - 2). |
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+0
1
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| 1, 2, 1, -1, -4, -1, -1, 4, 29, 1, -20, -29, -299, 20, 559, 299, 3926, -559, -13429, -3926, -61165, 13429, 343174, 61165, 1063621, -343174, -9642971, -1063621, -19074796, 9642971, 298720955, 19074796, 292597721, -298720955, -10150389236, -292597721, -90530999, 10150389236, 375654932731
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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Even:a(n)=(n - 1)*a(n - 1) - a(n - 2) Odd:a(n)=a(n - 1) - (n - 2)*a(n - 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, (n - 1)*a[n - 1] - a[n - 2], a[n - 1] - (n -2)*a[n - 2]] Table[a[n], {n, 0, 50}]
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CROSSREFS
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Sequence in context: A008307 A099238 A061462 this_sequence A005131 A105477 A127709
Adjacent sequences: A122575 A122576 A122577 this_sequence A122579 A122580 A122581
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KEYWORD
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sign,uned
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AUTHOR
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Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 17 2006
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