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%I #13 Nov 18 2012 12:34:32
%S 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,
%T 47,50,51,54,58,60,60,60,61,64,69,72,72,74,76,74,75,82,87,86,86,90,90,
%U 88,93,100,101,100,102,104,104,106,111,114,115,116,116,118,122
%N Coordination sequence for VPl-5 structure with respect to node (X) where 18-gon and two squares meet.
%C There are two types of nodes in this structure.
%C 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.
%H Joseph Myers, <a href="/A072152/b072152.txt">Table of n, a(n) for n = 0..1000</a>
%H M. E. Davis, <a href="http://dx.doi.org/10.1038/nature00785">Ordered porous materials for emerging applications</a>, Nature, 417 (Jun 20 2002), 813-821 (gives structure).
%H N. J. A. Sloane, <a href="/A072152/a072152.gif">VPl-5 structure, after Davis</a>
%F 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]
%Y Cf. A072149-A072154.
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_, Jun 28 2002
%E Extended by _Joseph Myers_, Sep 30 2011
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