A036656 Number of n-node rooted unlabeled trees with outdegree <= 2 and exactly 1 edge at the root.

0, 0, 1, 1, 2, 3, 6, 11, 23, 46, 98, 207, 451, 983, 2179, 4850, 10905, 24631, 56011, 127912, 293547, 676157, 1563372, 3626149, 8436379, 19680277, 46026618, 107890609, 253450711, 596572387, 1406818759, 3323236238, 7862958391

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Index entries for sequences related to rooted trees

Crossrefs

Except for initial terms, same as A001190.

Programs

Maple

G036656 := G001190-x; A036656 := n->coeff(G036656,x,n);

Mathematica

terms = 33; A[] = 0; Do[A[x] = x + (1/2)*(A[x]^2 + A[x^2]) + O[x]^terms // Normal, terms];
CoefficientList[A[x] - x, x] (* Jean-François Alcover, Jan 24 2018 *)