cp's OEIS Frontend

A057712 Number of "polyhes" of order n: a polyhe of order n is obtained by taking a polyhex made of n hexagons (A000228); cutting each of the n hexagons along a diameter and throwing away half that hexagon, in such a way that the remaining figure (made of n half-hexagons) is connected.

%I A057712 #15 Feb 16 2025 08:32:43
%S A057712 1,4,13,60,276,1416,7201,37972,201989,1089815,5929666,32533673,
%T A057712 179657435
%N A057712 Number of "polyhes" of order n: a polyhe of order n is obtained by taking a polyhex made of n hexagons (A000228); cutting each of the n hexagons along a diameter and throwing away half that hexagon, in such a way that the remaining figure (made of n half-hexagons) is connected.
%D A057712 Enumeration of a(1)-a(8) attributed by Andrew Clarke to Brendan Owen.
%H A057712 Abaroth's World, <a href="https://abarothsworld.com/Puzzles/Polyiamonds/Polyhes.htm">Polyhes, Polyhalfhexes & Polytriamonds</a>
%H A057712 Andrew Clarke, <a href="http://www.recmath.com/PolyPages/PolyPages/Polyhes.htm">Polyhes</a>
%H A057712 Andrew Clarke, <a href="/A057712/a057712.gif">Picture showing triangle formed by combining polyhes of orders 1, 2 and 3</a>.
%H A057712 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polyhe.html">Polyhe</a>
%K A057712 nonn,nice,hard,more
%O A057712 1,2
%A A057712 _N. J. A. Sloane_, Oct 27 2000
%E A057712 Link updated by _William Rex Marshall_, Dec 16 2009
%E A057712 a(9)-a(13) from _Aaron N. Siegel_, May 23 2022