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Search: id:A101561
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| A101561 |
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a(n)=(-1)^n*coefficient of x^n in sum{k>=1,x^(k-1)/(1+3x^k)}. |
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+0
3
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| 1, 2, 10, 29, 82, 236, 730, 2216, 6571, 19604, 59050, 177410, 531442, 1593596, 4783060, 14351123, 43046722, 129133838, 387420490, 1162281098, 3486785140, 10460294156, 31381059610, 94143358424, 282429536563, 847288078004
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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a(n)=sum{k=0..n, (-1)^(n-k)*if(mod(n+1, k+1)=0, 1, 0)*3^k}
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CROSSREFS
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Cf. A051731, A081295, A048272, A101562, A101563.
Adjacent sequences: A101558 A101559 A101560 this_sequence A101562 A101563 A101564
Sequence in context: A127921 A106184 A076438 this_sequence A047112 A032250 A133485
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KEYWORD
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easy,nonn
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AUTHOR
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Paul Barry (pbarry(AT)wit.ie), Dec 07 2004
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