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A052808 E.g.f.: -log(1-x+log(1-x)). 0
0, 2, 5, 24, 169, 1572, 18208, 252676, 4088138, 75571648, 1571427096, 36304942704, 922615912656, 25577663099232, 768176940800592, 24845381066244288, 860979848497650768, 31825036424306681088, 1249895536243141292544, 51975908060575367916288 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Previous name was: A simple grammar.

LINKS

Table of n, a(n) for n=0..19.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 770

FORMULA

E.g.f.: -log(1-x+log(1-x)). - Michael Somos, Sep 21, 2002

a(n) ~ (n-1)! / (1-LambertW(1))^n. - Vaclav Kotesovec, Oct 01 2013

MAPLE

spec := [S, {C=Cycle(Z), B=Union(C, Z), S=Cycle(B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

MATHEMATICA

With[{nn=30}, CoefficientList[Series[-Log[1-x+Log[1-x]], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Mar 27 2013 *)

PROG

(PARI) a(n)=if(n<0, 0, n!*polcoeff(-log(1-x+log(1-x+x*O(x^n))), n))

CROSSREFS

Sequence in context: A020124 A012249 A303108 * A137157 A025134 A076534

Adjacent sequences:  A052805 A052806 A052807 * A052809 A052810 A052811

KEYWORD

easy,nonn

AUTHOR

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

EXTENSIONS

More terms from Harvey P. Dale, Mar 27 2013

New name, using e.g.f., by Vaclav Kotesovec, Oct 01 2013

STATUS

approved

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Last modified May 27 02:54 EDT 2019. Contains 323597 sequences. (Running on oeis4.)