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A052808
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E.g.f.: -log(1-x+log(1-x)).
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2
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0, 2, 5, 24, 169, 1572, 18208, 252676, 4088138, 75571648, 1571427096, 36304942704, 922615912656, 25577663099232, 768176940800592, 24845381066244288, 860979848497650768, 31825036424306681088, 1249895536243141292544, 51975908060575367916288
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OFFSET
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0,2
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COMMENTS
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Previous name was: A simple grammar.
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LINKS
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FORMULA
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MAPLE
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spec := [S, {C=Cycle(Z), B=Union(C, Z), S=Cycle(B)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);
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MATHEMATICA
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With[{nn=30}, CoefficientList[Series[-Log[1-x+Log[1-x]], {x, 0, nn}], x] Range[ 0, nn]!] (* Harvey P. Dale, Mar 27 2013 *)
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PROG
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(PARI) a(n)=if(n<0, 0, n!*polcoeff(-log(1-x+log(1-x+x*O(x^n))), n))
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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STATUS
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approved
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