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Search: id:A126285
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| A126285 |
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Number of partial mappings (or mapping patterns) from n points to themselves; number of partial endofunctions. |
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+0
4
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| 1, 2, 6, 16, 45, 121, 338, 929, 2598, 7261, 20453, 57738, 163799, 465778, 1328697, 3798473, 10883314, 31237935, 89812975, 258595806, 745563123, 2152093734, 6218854285, 17988163439, 52078267380, 150899028305, 437571778542
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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If an endofunction is partial, then some points may be unmapped (or mapped to "undefined").
The labeled version is left-shifted A000169. - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Jan 16 2007
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LINKS
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N. J. A. Sloane, Transforms
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FORMULA
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Euler transform of A002861 + A000081 = [1, 2, 4, 9, 20, 51, 125, 329, 862, 2311, ... ] + [ 1, 1, 2, 4, 9, 20, 48, 115, 286, 719, ...] = A124682.
Convolution of left-shifted A000081 with A001372. - Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Jan 16 2007
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CROSSREFS
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Cf. A001372.
Cf. A000169, A000081, A002861.
Sequence in context: A105696 A074413 A055544 this_sequence A026163 A005717 A025266
Adjacent sequences: A126282 A126283 A126284 this_sequence A126286 A126287 A126288
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KEYWORD
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nonn
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AUTHOR
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Christian G. Bower (bowerc(AT)usa.net), Dec 25 2006 based on a suggestion from Jonathan Vos Post
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