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%I #34 Apr 16 2023 09:23:11
%S 1,1,3,7,20,62,204,709,2526,9212,33989,126838,476597,1802618,6850969,
%T 26153537,100207548,385225375,1485216987,5741272625,22246000726,
%U 86383442996,336093551268,1309998354125,5114452295933,19998173607505,78306014924606,307022185565345
%N Number of diamond polyominoes with n cells.
%C Also the number of polybricks of size n made of Lego.
%H John Mason, <a href="/A056783/b056783.txt">Table of n, a(n) for n = 1..50</a>
%H Ed Pegg, Jr., <a href="http://demonstrations.wolfram.com/PolyformExplorer/">Illustrations of polyforms</a>.
%H M. Keller, <a href="http://www.solitairelaboratory.com/polyenum.html">Counting Polyforms</a>.
%H M. Vicher, <a href="http://www.vicher.cz/puzzle/polyforms.htm">Polyforms</a>.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Polyrhomb.html">Polyrhomb</a>.
%F a(n) = 2*A006749(n) + A006746(n) + 2*A006748(n) + 2*A006747(n) + A056877(n) + 2*A056878(n) + A144553(n) + A142886(n). - _Andrew Howroyd_, Dec 04 2018
%Y Cf. A000105, A056780, A057973, A151522.
%K nonn,hard
%O 1,3
%A _James A. Sellers_, Aug 28 2000
%E More terms from _Don Reble_, Nov 01 2001
%E a(15)-a(18) from _Joseph Myers_, Nov 15 2010
%E Offset corrected and a(19)-a(28) from _Andrew Howroyd_, Dec 04 2018
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