# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a342963 Showing 1-1 of 1 %I A342963 #16 Apr 20 2021 10:08:26 %S A342963 1,2,15,110,1051,10636,113290,1234189,13674761,153289285 %N A342963 a(n) is the number of sticky polyhexes of with 2*n cells. %C A342963 A sticky polyhex is defined as follows: %C A342963 - A single dihex (polyhex of size 2) is a sticky polyhex. %C A342963 - If a polyhex X is sticky, X plus a dihex Y is also sticky if X and Y share at least two unit sides. %C A342963 - Any polyhex that cannot be formed by the above definition is not sticky. %C A342963 This sequence counts free polyhexes; two polyhexes which are equivalent under reflection and/or rotation are counted only once. %C A342963 a(n) < A000228(2n) for n > 1. %H A342963 Woosuk Kwak, Sticky Polyhexes, Code Golf Stack Exchange. %e A342963 The two sticky tetrahexes are: %e A342963 * * * * * %e A342963 * * * %e A342963 The following is the full list of 15 sticky hexahexes (polyhexes of size 6): %e A342963 * * * * * * * * * * * * * * %e A342963 * * * * * * * * * * * * * %e A342963 * * * %e A342963 --- %e A342963 * * * * * * * * * * %e A342963 * * * * * * * * * * * * * * * %e A342963 * * * * * %e A342963 --- %e A342963 * * * * * * * * * * * * * * * * %e A342963 * * * * * * * * * * %e A342963 * * * * %Y A342963 Cf. A000228. %K A342963 nonn,hard,more %O A342963 1,2 %A A342963 _Woosuk Kwak_, Mar 31 2021 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE