A072152 Coordination sequence for VPl-5 structure with respect to node (X) where 18-gon and two squares meet.

1, 3, 4, 6, 8, 8, 10, 14, 16, 17, 20, 23, 22, 22, 28, 32, 30, 31, 36, 37, 36, 40, 46, 46, 44, 47, 50, 51, 54, 58, 60, 60, 60, 61, 64, 69, 72, 72, 74, 76, 74, 75, 82, 87, 86, 86, 90, 90, 88, 93, 100, 101, 100, 102, 104, 104, 106, 111, 114, 115, 116, 116, 118, 122

Offset: 0

Author

N. J. A. Sloane, Jun 28 2002

Keywords

• nonn
• easy

Comments

There are two types of nodes in this structure.

The coordination sequence with respect to a particular node gives the number of nodes that can be reached from that node in n steps along edges.

Links

• Joseph Myers, Table of n, a(n) for n = 0..1000
• M. E. Davis, Ordered porous materials for emerging applications, Nature, 417 (Jun 20 2002), 813-821 (gives structure).
• N. J. A. Sloane, VPl-5 structure, after Davis

Crossrefs

Cf. A072149-A072154.

Formula

Empirical G.f.: -(x^17+x^16-x^15-2*x^14-2*x^13-2*x^12-4*x^11-5*x^10-5*x^9-5*x^8-7*x^7-6*x^6-4*x^5-4*x^4-4*x^3-2*x^2-2*x-1)/((x-1)^2*(x^2+1)*(x^4+1)*(x^6+x^5+x^4+x^3+x^2+x+1)). [Colin Barker, Nov 18 2012]

Extensions

Extended by Joseph Myers, Sep 30 2011