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A131623
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Number of blocks in all partitions of n-set with distinct block sizes.
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1
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1, 1, 7, 9, 31, 223, 442, 1529, 6559, 66111, 159952, 742503, 3047656, 19094286, 245173117, 761328969, 3935539271, 20213664703, 117323673136, 897132508439, 15791065424134, 56649181720176, 353387529508691, 1955231849465423
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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FORMULA
| E.g.f.: Sum(x^n/(n!+x^n),n=1..inf)*Product(1+x^n/n!,n=1..inf).
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MAPLE
| A131623 := proc(n) local su, i ; su := add(x^i/(i!+x^i), i=1..n+1) ; for i from 1 to n do su := taylor(su*(1+x^i/i!), x=0, n+1) ; od: n!*coeftayl(su, x=0, n) ; end: seq(A131623(n), n=1..30) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 25 2007
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CROSSREFS
| Cf. A044048, A007837.
Sequence in context: A200180 A147248 A147186 * A032011 A177030 A189974
Adjacent sequences: A131620 A131621 A131622 * A131624 A131625 A131626
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KEYWORD
| easy,nonn
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AUTHOR
| Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 02 2007
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EXTENSIONS
| More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 25 2007
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