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Search: id:A059777
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| A059777 |
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Number of self-conjugate three-quadrant Ferrers graphs that partition n. |
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4
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| 1, 0, 1, 1, 2, 2, 3, 4, 6, 7, 9, 12, 16, 19, 24, 31, 39, 47, 58, 72, 89, 107, 129, 158, 192, 228, 273, 329, 393, 465, 551, 655, 776, 911, 1070, 1261, 1480, 1726, 2014, 2354, 2742, 3180, 3688, 4279, 4954, 5716, 6590, 7603, 8754, 10049, 11532
(list; graph; listen)
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OFFSET
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0,5
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REFERENCES
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G. E. Andrews, Three-quadrant Ferrers graphs, Indian J. Math., 42 (No. 1, 2000), 1-7.
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FORMULA
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G.f.: 1/(1+x)*1/Sum_{k>0} (-x)^(k*(k+1)/2). a(n)=1/n*Sum_{k=1..n} (-1)^(k+1)*(A002129(k)-1)*a(n-k). A006950(n) = a(n-1)+a(n), n>0. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Sep 22 2002
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MAPLE
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mul((1+q^(2*n+3))/(1-q^(2*n+2)), n=0..101); # g.f.
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CROSSREFS
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Cf. A059776, A059778.
Sequence in context: A039908 A093950 A023894 this_sequence A017830 A026928 A102464
Adjacent sequences: A059774 A059775 A059776 this_sequence A059778 A059779 A059780
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KEYWORD
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nonn
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AUTHOR
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njas, Feb 21 2001
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