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A072152 Coordination sequence for VPl-5 structure with respect to node (X) where 18-gon and two squares meet. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A069211 A242822 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

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Last modified August 19 06:42 EDT 2017. Contains 290794 sequences.