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A032187
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Shifts left 3 places under "CIJ" (necklace, indistinct, labeled) transform.
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1
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1, 1, 1, 1, 2, 6, 26, 151, 1093, 9489, 96084, 1111722, 14469388, 209234595, 3328056991, 57746229265, 1085448899206, 21972175778646, 476535125344462, 11024061833485335, 270965694793159153, 7051933526740491393, 193723061625591928384, 5601822117610355927946
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OFFSET
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1,5
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LINKS
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FORMULA
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a(n) = sum(k=0..n-5, binomial(n-4,k)*a(k+4)*a(n-k-4)) + a(n-3), n>4, a(1)=a(2)=a(3)=a(4)=1. - Vladimir Kruchinin, May 10 2011
E.g.f. A(x) satisfies differential equation A'''(x)=log(1/(1-A(x))), A'(0)=1, A''(0)=1, A'''(0)=1. - Vladimir Kruchinin, Nov 19 2011
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PROG
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(Maxima)
a(n):=if n=0 then 0 else if n<5 then 1 else sum(binomial(n-4, k)*a(k+4)*a(n-k-4), k, 0, n-5)+a(n-3); /* Vladimir Kruchinin, May 10 2011 */
(PARI)
CIJ(p)={-log(1-p)}
seq(n)={my(p=x+x^2+O(x*x^(n%3))); for(i=1, n\3, p=intformal(1 + intformal(1 + intformal(1 + CIJ(p))))); Vec(serlaplace(p))} \\ Andrew Howroyd, Sep 19 2018
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CROSSREFS
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KEYWORD
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nonn,eigen
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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