This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A159944 #11 Dec 12 2015 01:13:34 %S A159944 0,1,4,11,26,46,84,123,194,268,378,478,657,800,1019,1239,1548,1793, %T A159944 2197,2505,3003,3434,3991,4444,5223,5801,6582,7292,8274,9006,10199, %U A159944 11034,12330,13398,14744,15912,17705,18906,20586 %N A159944 Number of different deltoids (including squares) whose vertices are on an n X n grid. %C A159944 Only convex kites (A189417) are counted, not concave kites (A173502), distinct up to congruence. %H A159944 Nathaniel Johnston, <a href="/A159944/a159944.c.txt">C program for computing terms</a> %e A159944 a(1) = 0, since there is only one point on a 1 X 1 grid. %e A159944 a(2) = 1, since the four points on a 2 X 2 grid build a 1 X 1 square. %e A159944 a(3) = 4 since there are 3 sizes of squares on a 3 X 3 grid -- 1 X 1, 2 X 2, sqrt(2) X sqrt(2) -- and a single nonsquare deltoid. %Y A159944 Cf. A189417, A173502. %K A159944 nonn %O A159944 1,3 %A A159944 Demacek Ondrej (demacek(AT)gjh.sk), Apr 27 2009 %E A159944 Edited by _Ray Chandler_, May 01 2011 %E A159944 Corrected and extended by _Nathaniel Johnston_ with help from _Ray Chandler_, May 11 2011