A004040 Inversion of A000257.

1, 2, 6, 23, 103, 512, 2740, 15485, 91245, 555662, 3475090, 22214707, 144640291, 956560748, 6411521056, 43478151737, 297864793993, 2059159989914, 14350039389022, 100726680316559, 711630547589023, 5057282786190872, 36132861123763276, 259423620328055093, 1870954187618001253

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

Crossrefs

Cf. A000257.

Essentially the same as A022558.

Programs

PARI

x='x+O('x^66); Vec( -1 + 32*x/(1+20*x-8*x^2-(1-8*x)^(3/2)) ) \\ Joerg Arndt, May 04 2013

Formula

Invert: define b by 1+Sum a(n)x^n = 1/(1 - Sum b(n)x^n).

Extensions

More terms from Joerg Arndt, May 04 2013