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 A006989 Log of g.f. of numbers of preferential arrangements. 1
 1, 0, 2, 4, 34, 196, 1826, 17172, 199074, 2510116, 35862562, 559572916, 9577862306, 177417693636, 3546104002338, 75961485384532, 1737273637523362, 42235881659123812, 1087865420946370082, 29589907884231535860, 847576876148087333538, 25501591020532799366404 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS If A= e.g.f. for A006989 and B = e.g.f. for A000670, then A = log(1+\int(B))'. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 R. G. Wilson v, Letter to N. J. A. Sloane, Jan. 1993 MATHEMATICA CoefficientList[Series[2/((2 - E^x)*(2 + x - Log[2 - E^x])), {x, 0, 20}], x] * Range[0, 20]! (* Vaclav Kotesovec, Feb 24 2014 *) PROG (PARI) a(n)=if(n<0, 0, n!*polcoeff(log(1+intformal(1/(2-exp(x+x*O(x^n)))))', n)) CROSSREFS Cf. A000670. Sequence in context: A099433 A051225 A103625 * A236399 A132529 A140984 Adjacent sequences:  A006986 A006987 A006988 * A006990 A006991 A006992 KEYWORD nonn AUTHOR STATUS approved

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Last modified March 21 01:18 EDT 2019. Contains 321356 sequences. (Running on oeis4.)