

A072152


Coordination sequence for VPl5 structure with respect to node (X) where 18gon and two squares meet.


3



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
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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), 813821 (gives structure).
N. J. A. Sloane, VPl5 structure, after Davis


FORMULA

Empirical G.f.: (x^17+x^16x^152*x^142*x^132*x^124*x^115*x^105*x^95*x^87*x^76*x^64*x^54*x^44*x^32*x^22*x1)/((x1)^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. A072149A072154.
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



