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 A118282 #3 Mar 30 2012 17:22:42 %S A118282 0,-1,0,0,307,-1,2027,5200,18180,-1,10795,-1,87740,-1,75150,212048, %T A118282 122818,-1,146970,199153,585513 %N A118282 Conjectured largest number that is not the sum of three generalized n-gonal numbers, or -1 if there is no largest number. %C A118282 Extensive calculations show that if a(n)>=0, then every number greater than a(n) can be represented as the sum of three generalized n-gonal numbers. a(n)=0 for n=3 and 6 because generalized triangular and generalized hexagonal numbers are the same a triangular numbers and every number can be written as the sum of three triangular numbers. When n is a multiple of 4, there is an infinite set of numbers not representable. For n=14, there appears to be a sparse, but infinite, set of numbers not representable. See A118283 for the number of numbers not representable. %Y A118282 Cf. A001318 (generalized pentagonal numbers), A085787 (generalized heptagonal numbers), A001082 (generalized octagonal numbers), A118277 (generalized 9-gonal numbers), A118278-A118285. %K A118282 sign %O A118282 3,5 %A A118282 _T. D. Noe_, Apr 21 2006