A294167 Column 1 of triangle A291843.

3, 33, 388, 5101, 75444, 1248911, 22964112, 465344235, 10316541393, 248583207948, 6472094085480, 181133509590584, 5424172954377851, 173089061380034193, 5864328868997378224, 210259284591708083349, 7954221480382049449284, 316654854011156144727459, 13233287747652092826502116

Offset: 3

Author

Gheorghe Coserea, Nov 06 2017

Keywords

• nonn

Links

• Gheorghe Coserea, Table of n, a(n) for n = 3..305

Crossrefs

Cf. A291843.

Programs

PARI

A291843_ser(N, t='t) = {
  my(x='x+O('x^N), y=1, y1=0, n=1,
  dn = 1/(-2*t^2*x^4 - (2*t^2+3*t)*x^3 - (2*t+1)*x^2 + (2*t-1)*x + 1));
  while (n++,
   y1 = (2*x^2*y'*((-t^2 + t)*x + (-t + 1) + (t^2*x^2 + (t^2 + t)*x + t)*y) +
        (t*x^2 + t*x)*y^2 - (2*t^2*x^3 + 3*t*x^2 + (-t + 1)*x - 1))*dn;
   if (y1 == y, break); y = y1; ); y;
};
A291843_kol(k, N=19) = {
  my(s = A291843_ser(N+1+3*(k+1)\2, t='t + O('t^(k+1))));
  Ser(polcoeff(s, k, 't), 'x, N);
};
Vec(A291843_kol(1))