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Search: id:A107321
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| A107321 |
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a(n)=Sum(i+j+k+l+...+r+s=n) A005316(i)*A005316(j)*...*A005316(s) and the ordered partition of n runs over all odd i, all even j,k,.., r, all i,j,...,r,s>=1. |
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+0
3
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| 1, 1, 2, 3, 8, 14, 42, 79, 254, 506, 1702, 3548, 12320, 26666, 94794, 211751, 766362, 1758352, 6453812, 15150922, 56238710, 134659120
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OFFSET
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0,3
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COMMENT
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A lower bound to A076876. a(n) counts the cases where all crossings k are East of the crossings i, all crossings l East of the crossings j etc. Some backwinding interlaced crossings are counted in A076876(n) but not here.
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CROSSREFS
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Sequence in context: A049344 A080877 A007165 this_sequence A005316 A076876 A124495
Adjacent sequences: A107318 A107319 A107320 this_sequence A107322 A107323 A107324
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KEYWORD
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nonn
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AUTHOR
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R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 06 2006
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