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%I M5304 N2306 #19 Feb 09 2016 07:39:40
%S 52,472,3224,18888,101340,511120,2465904,11496144,52165892,231557064,
%T 1009247192,4331502840,18346242492,76822836544,318485778848,
%U 1308750158016,5335993098340,21603437175288,86912657626392,347660876627944,1383457374046444,5479086968052912,21604984733546336,84850331177724944,332001521469767940,1294589169323791912,5031934808360234760,19500424806065865400,75360646947991208396,290478417300879735680,1116919455364101145920,4284817000807140094464,16402243457215852326116,62659647762404302956856,238910441445219175239480
%N Series-parallel numbers.
%D J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 142.
%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%F G.f.: 4(13+14S+3S^2)(1+S)/(1-S)^7, where S = g.f. for A000084. - _Sean A. Irvine_, Nov 14 2010
%t n = 35; s = 1/(1 - x) + O[x]^(n + 1); Do[s = s/(1 - x^k)^Coefficient[s, x^k] + O[x]^(n + 1), {k, 2, n}] ; S = s - 1; CoefficientList[4 (13 + 14 S + 3 S^2) (1 + S)/(1 - S)^7 + O[x]^n, x] (* _Jean-François Alcover_, Feb 09 2016 *)
%K nonn
%O 4,1
%A _N. J. A. Sloane_
%E More terms from _Sean A. Irvine_, Nov 14 2010
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