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A168268
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G.f.: exp( Sum_{n>=1} A007837(n)*x^n/n ), where A007837(n) = number of partitions of n-set with distinct block sizes.
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2
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1, 1, 1, 2, 3, 6, 20, 45, 116, 385, 2224, 6396, 23708, 88065, 445784, 3962502, 14478825, 64495508, 309085415, 1608099881, 10856426344, 142802148953, 604464533847, 3324499738872, 17795211310951, 112537384959231, 718232376832560
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OFFSET
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0,4
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COMMENTS
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Conjectured to consist entirely of integers.
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LINKS
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EXAMPLE
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G.f.: A(x) = 1 + x + x^2 + 2*x^3 + 3*x^4 + 6*x^5 + 20*x^6 + 45*x^7 +...
log(A(x)) = x + x^2/2 + 4*x^3/3 + 5*x^4/4 + 16*x^5/5 + 82*x^6/6 + 169*x^7/7 + 541*x^8/8 +...+ A007837(n)*x^n/n +...
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PROG
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(PARI) {a(n)=polcoeff(exp(serlaplace(intformal((-1+prod(k=1, n+1, 1+x^k/k! +x^2*O(x^n)))/x))), n)}
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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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