A063786 G.f.: A(x) = (x-2*x^2-2*x^3-(1+x)*sqrt(1-4*x^2)+sqrt(1-4*x^6))/(2*x^2).

1, 1, 1, 2, 5, 5, 14, 14, 41, 42, 132, 132, 429, 429, 1428, 1430, 4862, 4862, 16796, 16796, 58781, 58786, 208012, 208012, 742900, 742900, 2674426, 2674440, 9694845, 9694845, 35357670, 35357670, 129644748, 129644790, 477638700, 477638700

Offset: 2

Author

Vladeta Jovovic, Aug 24 2001

Keywords

• nonn

References

• F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 78, (3.5.30). ( A(x) = s_1 bar (x) ).

Crossrefs

Cf. A000108, A000207.