A203900 a(n)=f(a(n-1)+1,a(n-2),a(n-3)+1), where f(x,y,z)=yz+zx+xy and (a(1),a(2),a(3))=(0,0,1).

0, 0, 1, 2, 7, 36, 391, 17536, 7520303, 134830884224, 1016333764230127711, 137040823237740906153712364032, 139279234211744145176797121311869355242595356863

Offset: 1

Author

Clark Kimberling, Jan 07 2012

Keywords

• nonn

Comments

For a guide to related sequences, see A203761.

Crossrefs

Cf. A203761.

Programs

Mathematica

a[1] = 0; a[2] = 0; a[3] = 1;
a[n_] := SymmetricPolynomial[2, {1 + a[n - 1], a[n - 2], 1 + a[n - 3]}]
Table[a[n], {n, 1, 16}]  (* A203900 *)