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A004797
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Convolution of A002024 with itself.
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1
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1, 4, 8, 14, 22, 30, 41, 54, 67, 82, 99, 118, 138, 160, 182, 206, 234, 262, 292, 322, 353, 388, 425, 462, 501, 542, 583, 626, 671, 718, 766, 818, 870, 922, 976, 1030, 1088, 1148, 1210, 1274, 1338, 1402, 1469, 1538, 1607, 1678, 1753, 1828, 1905, 1984, 2063
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: (1/(1 - x)^2)*Product_{k>=1} (1 - x^(2*k))^2/(1 - x^(2*k-1))^2. - Ilya Gutkovskiy, May 30 2017
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MAPLE
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a002024:= [seq(i$i, i=1..10)]:
g002024:= add(a002024[i]*x^(i-1), i=1..nops(a002024)):
g:= expand(g002024^2):
seq(coeff(g, x, i), i=0..degree(g002024)); # Robert Israel, May 30 2017
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PROG
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(PARI) nn(n)=(sqrtint(n*8)+1)\2;
a(n) = sum(k=1, n, nn(k)*nn(n-k+1)); \\ Michel Marcus, May 30 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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