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 A181946 #19 Feb 16 2025 08:33:13 %S A181946 0,1,4,11,25,45,81,121,188,261,368,469,641,785,1000,1220,1520,1767, %T A181946 2161,2471,2961,3396,3946,4403,5164,5744,6517,7227,8201,8936,10122, %U A181946 10963,12240,13312,14649,15839,17607,18813,20482,21983,24111,25589,27920,29550,31979 %N A181946 Number of kites, distinct up to congruence, on an n X n grid (or geoboard). %C A181946 Only convex kites are counted, not concave kites (sometimes called darts or arrowheads). %H A181946 Lucas A. Brown, <a href="https://github.com/lucasaugustus/oeis/blob/main/A181946.py">Python program</a>. %H A181946 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Kite.html">Kite</a>. %e A181946 a(1) = 0 because the 1 X 1 grid has no kites. %e A181946 a(2) = 1 because the 2 X 2 grid has one kite. %e A181946 a(3) = 4 because the 3 X 3 grid has 4 congruence classes of kites, out of 10 kites total: %e A181946 +-------+-------+-------+-------+ %e A181946 | . . . | o . o | . . o | . o . | %e A181946 | o o . | . . . | o . . | o . o | %e A181946 | o o . | o . o | o o . | . o . | %e A181946 +-------+-------+-------+-------+ %Y A181946 Cf. A181944, A189417. %K A181946 nonn %O A181946 1,3 %A A181946 _Martin Renner_, Apr 03 2012 %E A181946 a(7)-a(45) from _Lucas A. Brown_, Feb 08 2024