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 A063773 #6 Mar 30 2012 18:35:41 %S A063773 4,10,19,31,61,211,181,361,631,841,1261,5461,2521,6931,18481,20791, %T A063773 13861,27721,41581,83161,138601,245701,235621,180181,556921,360361, %U A063773 540541,1670761,1081081,1413721,2162161,3603601,4324321,3063061 %N A063773 Smallest number that is centered polygonal in exactly n ways. %H A063773 Donovan Johnson, <a href="/A063773/b063773.txt">Table of n, a(n) for n = 1..90</a> %e A063773 19 is the smallest number that is centered k-gonal for exactly three k (k = 3, 6, or 18). Hence a(3) = 19 %K A063773 nonn %O A063773 1,1 %A A063773 _David W. Wilson_, Aug 15 2001