A215980 Number of simple unlabeled graphs on n nodes with exactly 10 connected components that are trees or cycles.

1, 1, 3, 6, 13, 26, 56, 115, 247, 533, 1175, 2635, 6037, 14069, 33378, 80466, 196759, 487453, 1221515, 3092719, 7901816, 20354765, 52815434, 137946253, 362430959, 957359614, 2541249138, 6775848932, 18141119582, 48753971355, 131485310625, 355759469235

Offset: 10

Author

Alois P. Heinz, Aug 29 2012

Keywords

• nonn

Examples

			a(12) = 3: .o-o o o o o.  .o-o o o o o.  .o o o o o o.
           .|/         .  .|          .  .| |        .
           .o o o o o o.  .o o o o o o.  .o o o o o o.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 10..650

Crossrefs

Column k=10 of A215977.

The labeled version is A215860.

Programs

Maple

with(numtheory):
b:= proc(n) option remember; local d, j; `if`(n<=1, n,
      (add(add(d*b(d), d=divisors(j)) *b(n-j), j=1..n-1))/(n-1))
    end:
g:= proc(n) option remember; local k; `if`(n>2, 1, 0)+ b(n)-
      (add(b(k)*b(n-k), k=0..n) -`if`(irem(n, 2)=0, b(n/2), 0))/2
    end:
p:= proc(n, i, t) option remember; `if`(n p(n, n, 10):
seq(a(n), n=10..50);