A198015 Number of isomorphism classes of nanocones with 4 pentagons and a symmetric boundary of length n.

1, 4, 16, 37, 89, 175, 336, 579, 975, 1533, 2363, 3477, 5030, 7040, 9716, 13078, 17400, 22707, 29342, 37336, 47112, 58705, 72627, 88918, 108185, 130476, 156502, 186315, 220741, 259839, 304554, 354953, 412111, 476101, 548137, 628299, 717946, 817168, 927478

Offset: 2

Author

Nico Van Cleemput, Oct 20 2011

Keywords

• nonn

Links

• Nico Van Cleemput, Table of n, a(n) for n = 2..75
• G. Brinkmann and N. Van Cleemput, Classification and generation of nanocones, Discrete Applied Mathematics, 159 (2011), 1528-1539.

Formula

Conjectured g.f.: x^2*(-x^11 + x^10 - x^9 + 4*x^8 + 5*x^7 + 10*x^6 + 9*x^5 + 11*x^4 + 4*x^3 + 7*x^2 + 2*x + 1) / ((x - 1)^6*(x + 1)^3*(x^2 + 1)*(x^2 + x + 1)). [D. S. McNeil, Oct 20 2011]