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A286797 Row sums of A286796. 2
1, 2, 10, 82, 898, 12018, 187626, 3323682, 65607682, 1424967394, 33736908874, 864372576626, 23825543471234, 703074672632018, 22118247888976170, 739081808704195650, 26146116129400483842, 976382058777174451650, 38386296866727499728522, 1584986693941237056394386 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Gheorghe Coserea, Table of n, a(n) for n = 0..200

Luca G. Molinari, Nicola Manini, Enumeration of many-body skeleton diagrams, arXiv:cond-mat/0512342 [cond-mat.str-el], 2006.

FORMULA

a(n) = Sum_{k=0..n} A286796(n,k).

MATHEMATICA

max = 20; y0[x_, t_] = 1; y1[x_, t_] = 0; For[n = 1, n <= max, n++, y1[x_, t_] = (1 + x*(1 + 2*t + x*t^2)*y0[x, t]^2 + t*(1 - t)*x^2*y0[x, t]^3 + 2*x^2*y0[x, t]*D[y0[x, t], x])/(1 + 2*x*t) + O[x]^n // Normal // Simplify; y0[x_, t_] = y1[x, t]];

a[n_] := CoefficientList[SeriesCoefficient[y0[x, t]/(1 - x*t*y0[x, t]), {x, 0, n}], t] // Total;

Table[a[n], {n, 0, max-1}] (* Jean-Fran├žois Alcover, May 24 2017, adapted from PARI *)

PROG

(PARI)

A286795_ser(N, t='t) = {

  my(x='x+O('x^N), y0=1, y1=0, n=1);

  while(n++,

    y1 = (1 + x*(1 + 2*t + x*t^2)*y0^2 + t*(1-t)*x^2*y0^3 + 2*x^2*y0*y0');

    y1 = y1 / (1+2*x*t); if (y1 == y0, break()); y0 = y1; ); y0;

};

A286796_ser(N, t='t) = my(v=A286795_ser(N, t)); v/(1-x*t*v);

Vec(A286796_ser(20, 1))

(PARI)

A049464_ser(N) = {  \\ for A049464(0)=0

  my(s=Ser(concat(1, vector(N+1, n, (2*n)!/(2^n*n!)))), g=(1/s - 1/s^2)/x);

  1 - 1/subst(g, 'x, serreverse(x*g^2*s^2));

};

A286797_ser(N) = my(q=A049464_ser(N)); q/(x-x*q);

Vec(A286797_ser(20))

CROSSREFS

Cf. A286796.

Sequence in context: A174962 A062396 A218294 * A321089 A112487 A089469

Adjacent sequences:  A286794 A286795 A286796 * A286798 A286799 A286800

KEYWORD

nonn

AUTHOR

Gheorghe Coserea, May 21 2017

STATUS

approved

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Last modified July 15 20:24 EDT 2019. Contains 325056 sequences. (Running on oeis4.)