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

0,2

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

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]

Crossrefs

Cf. A072149-A072154.

Sequence in context: A242822 A295996 A240675 * A199015 A196098 A099356

Adjacent sequences: A072149 A072150 A072151 * A072153 A072154 A072155

Keyword

nonn,easy

Author

N. J. A. Sloane, Jun 28 2002

Extensions

Extended by Joseph Myers, Sep 30 2011

Status

approved