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Search: id:A091344
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| A091344 |
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a(n)=Sum(i!i^2 Stirling2(n,i)(-1)^(n-i),i=1,..,n) |
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+0
2
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| 0, 1, 7, 31, 115, 391, 1267, 3991, 12355, 37831, 115027, 348151, 1050595, 3164071, 9516787, 28599511, 85896835, 257887111, 774054547, 2322950071, 6970423075, 20914414951, 62749536307, 188261191831, 564808741315, 1694476555591
(list; graph; listen)
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OFFSET
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0,3
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FORMULA
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a(n) = 2*3^n-3*2^n+1. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Jan 01 2004
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MAPLE
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a:=n->sum((3^(n-j-1)-2^(n-2-j))*12, j=0..n): seq(a(n), n=-1..24); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 11 2007
with (combinat):a:=n->stirling2(n, 3)+stirling2(n+1, 3): seq(a(n), n=1..26); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 07 2007
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MATHEMATICA
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Table[Sum[i!i^2 StirlingS2[n, i](-1)^(n - i), {i, 1, n}], {n, 0, 30}]
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CROSSREFS
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Sequence in context: A055580 A097786 A006458 this_sequence A032197 A114289 A048775
Adjacent sequences: A091341 A091342 A091343 this_sequence A091345 A091346 A091347
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KEYWORD
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easy,nonn
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AUTHOR
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Mario Catalani (mario.catalani(AT)unito.it), Jan 01 2004
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