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A280775
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Number of monolithic chord diagrams with n chords.
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7
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1, 3, 11, 65, 573, 6547, 89639, 1414417, 25148617, 496416579, 10762275539, 254153371121, 6494217863461, 178558132802259, 5257524611172751, 165089697983580641, 5507950426778674129, 194605351254360182403, 7259714571747394749147, 285174902634083710549601
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: C(x/(1-x)^2), where C(x) is the g.f. for A000699.
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MATHEMATICA
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terms = 20;
c[_] = 0;
Do[c[x_] = x + x^2*D[c[x]^2/x, x] + O[x]^(terms+1) // Normal, terms];
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PROG
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(PARI)
my(a = vector(N)); a[1] = 1;
for (n=2, N, a[n] = sum(k=1, n-1, (2*k-1)*a[k]*a[n-k])); a;
};
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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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