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 A189418 #35 Feb 16 2025 08:33:14 %S A189418 0,1,6,22,66,151,312,564,984,1601,2478,3622,5242,7271,9856,13124, %T A189418 17296,22229,28286,35306,43850,53891,65520,78624,94272,111977,131990, %U A189418 154514,180290,208611,240840,276032,315720,359497,407470,460078,519018,582447,651232,725820,808416 %N A189418 Number of rhombi on an n X n grid (or geoboard). %H A189418 Ray Chandler, <a href="/A189418/b189418.txt">Table of n, a(n) for n = 1..1000</a> (first 92 terms from R. H. Hardin) %H A189418 Nathaniel Johnston, <a href="/A189418/a189418.c.txt">C program for computing terms</a> %H A189418 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Rhombus.html">Rhombus</a> %Y A189418 Cf. A181947, A189413, A189414. %K A189418 nonn %O A189418 1,3 %A A189418 _Martin Renner_, Apr 21 2011 %E A189418 a(6)-a(28) from _Nathaniel Johnston_, Apr 23 2011 %E A189418 Terms beyond a(28) by _R. H. Hardin_, May 04 2011