A044048 Catafusenes (see reference for precise definition).

1, 1, 3, 10, 37, 149, 630, 2713, 11899, 52789, 236345, 1066317, 4842531, 22117897, 101535659, 468233674, 2168094625, 10076216851, 46986691678, 219777820957, 1030892924479, 4848040645676, 22853639788127, 107970205586283

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn

References

• S. J. Cyvin et al., Enumeration and classification of certain polygonal systems...: annelated catafusenes, J. Chem. Inform. Comput. Sci., 34 (1994), 1174-1180.

Formula

G.f.: (6 - 18x^3 - (1-x)*(1-2x)*f(x) - 3*(1+2x)*f(x^2) - 2*f(x^3))/(12x^3), where f(x) = sqrt(1 - 6x + 5x^2) (follows from eq. (26) in Cyvin et al.).

Extensions

More terms from Emeric Deutsch, Mar 14 2004