A055358 Number of increasing mobiles (circular rooted trees) with n nodes and 4 leaves.

6, 96, 874, 6040, 35458, 187288, 920350, 4297240, 19332662, 84615152, 362772194, 1531122296, 6385177274, 26382771464, 108232980822, 441554515704, 1793612585550, 7261158583200, 29318205685050

Offset: 5

Author

Christian G. Bower, May 15 2000

Keywords

• nonn

Links

• Georg Fischer, Table of n, a(n) for n = 5..250
• Index entries for sequences related to mobiles

Crossrefs

Column 4 of A055356.

Formula

For n>0, a(n) = 31*2^(2*n - 3)/9 - 5*(n+2)*3^n/12 + (n^2 + 2*n + 2)*2^(n-2) - n^3/6 - n/4 - 1/18. - Vaclav Kotesovec, Mar 15 2022