A316321 Number of "nonlinear" trees on n nodes.

0, 0, 0, 0, 1, 4, 16, 51, 158, 463, 1330, 3742, 10438, 28877, 79619, 218997, 602079, 1655623, 4557604, 12564084, 34697544, 96006605, 266185703, 739530680, 2058786037, 5742859294, 16050179897, 44939957405, 126052336580, 354158412141

Offset: 1

Author

N. J. A. Sloane, Jul 02 2018, following a suggestion from Chris Kennedy, Jun 24 2018

Keywords

• nonn

Links

• J. H. Verner, High-order explicit Runge-Kutta pairs with low stage order, Applied Numerical Mathematics, 22 (1996), 345-347. See Table 2.

Crossrefs

Cf. A000081, A000295.

Formula

a(n) = 0 for n <= 4. Thereafter, a(n) = A000081(n) - (n-1) - A000295(n-2) = A000081(n) - 2^(n-2). For example, a(9) = 286 - 8 - 120 = 286 - 2^7 = 158.