A035318 Right-hand diagonal of A035309.

1, 1, 1, 10, 21, 483, 1485, 56628, 225225, 12317877, 59520825, 4304016990, 24325703325, 2208143028375, 14230536445125, 1564439686929000, 11288163762500625, 1463987089109939625, 11665426077721040625, 1749439028845202483250, 15230046989184655753125

Offset

0,4

Links

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

Formula

a(n) = T(n, floor(n/2)), where T(n,g) is defined by A035309. - Gheorghe Coserea, Mar 18 2016

Mathematica

a[0] = a[1] = 1;
a[n_] := a[n] = ((4n-2) Mod[n, 2] a[n-1] + (n-1)(2n-3)(2n-1) a[n-2])/(n+1);
Table[a[n], {n, 0, 20}] (* Jean-François Alcover, Aug 30 2019, from PARI *)

Prog

(PARI)
seq(N) = {
  my(a = vector(N)); a[1] = a[2] = 1;
  for (n = 3, N,
       a[n] = ((4*n-2)*(n%2)*a[n-1] + (n-1)*(2*n-3)*(2*n-1)*a[n-2])/(n+1));
  concat(1, a);
};
seq(20)  \\ Gheorghe Coserea, Jan 20 2017

Crossrefs

Cf. A035309.

Sequence in context: A368635 A336748 A041198 * A039821 A109326 A369120

Adjacent sequences: A035315 A035316 A035317 * A035319 A035320 A035321

Keyword

nonn

Author

N. J. A. Sloane.

Extensions

More terms from Gheorghe Coserea, Mar 18 2016

Status

approved