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 A194450 #20 Jan 05 2013 09:08:07 %S A194450 0,1,2,4,6,9,12,17,21,28,33,44,50,65,72,94,102,132,141,183,193,249, %T A194450 260,337,349,450,463,598,612,788,803,1034,1050,1347,1364,1749,1767, %U A194450 2257,2276,2903,2923,3715,3736,4738,4760,6015,6038,7613,7637,9595 %N A194450 Vertex number of a rectangular spiral which contains exactly between its edges the successive shells of the partitions of the positive integers. %C A194450 First differences give A194451, the length of the edges of the spiral. For more information see A135010 and A138121. %F A194450 a(2n-1) = A026905(n) + A000217(n) - n, if n >= 1. %F A194450 a(2n) = A026905(n) + A000217(n), if n >= 1. %Y A194450 Cf. A000041, A000217, A006128, A026905, A066186, A135010, A138121, A138879, A138880, A182703, A182994, A182995, A194451. %K A194450 nonn %O A194450 0,3 %A A194450 _Omar E. Pol_, Nov 01 2011