A203762 a(n)=f(a(n-1),a(n-2)+1,a(n-3)), where f(x,y,z)=yz+zx+xy and (a(1),a(2),a(3))=(0,0,1).

0, 0, 1, 1, 2, 8, 35, 403, 18020, 7924920, 146015988543, 1159796524860801383, 169358027383278750824815637192, 196420876345386921523978742421837032517974708496

Offset

1,5

Comments

For a guide to related sequences, see A203761.

Links

Table of n, a(n) for n=1..14.

Mathematica

a[1] = 0; a[2] = 0; a[3] = 1;
a[n_] := SymmetricPolynomial[2, {a[n - 1], 1 + a[n - 2], a[n - 3]}]
Table[a[n], {n, 1, 16}]  (* A203762 *)

Crossrefs

Cf. A203761.

Sequence in context: A257555 A007508 A122674 * A185635 A076122 A332607

Adjacent sequences: A203759 A203760 A203761 * A203763 A203764 A203765

Keyword

nonn

Author

Clark Kimberling, Jan 07 2012

Status

approved