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 A121388 #4 Mar 31 2012 13:23:38 %S A121388 3,5,7,9,13,11,15,21,17,19,25,35,33,29,23,27,65,39,49,37,31,45,63,85, %T A121388 51,57,41,43,75,105,99,145,55,69,53,47,125,175,117,147,169,87,77,61, %U A121388 59,81,325,195,153,171,185,91,93,73,67,135,189,425,255,165,207,205,95,121,89 %N A121388 Table read by antidiagonals which classifies the proper odd numbers by form (i,j) where i and j are the number of prime factors of the form 4k-1 and 4k+1 respectively. %e A121388 Table begins: %e A121388 Row(i,j) %e A121388 1: (1,0) 3,7,11,19,23,31,43,47,59,67,71,79,83,103,... (A002145) %e A121388 2: (0,1) 5,13,17,29,37,41,53,61,73,89,97,101,109,... (A002144) %e A121388 3: (2,0) 9,21,33,49,57,69,77,93,121,129,133,141,... (A107978) %e A121388 4: (1,1) 15,35,39,51,55,87,91,95,111,115,119,... (A080774) %e A121388 5: (0,2) 25,65,85,145,169,185,205,221,265,289,... (A121387) %e A121388 6: (3,0) 27,63,99,147,171,207,231,279,343,... %e A121388 7: (2,1) 45,105,117,153,165,245,261,273,... %e A121388 8: (1,2) 75,175,195,255,275,435,455,... %e A121388 9: (0,3) 125,325,425,725,845,925,... %e A121388 10:(4,0) 81,189,297,441,513,... %e A121388 11:(3,1) 135,315,351,459,... %e A121388 12:(2,2) 225,525,585,... %e A121388 13:(1,3) 375,875,... %e A121388 14:(0,4) 625,... %Y A121388 Cf. A120027. Subsequences begin A002145 A002144 A107978 A080774 A121387. %K A121388 nonn,tabl %O A121388 1,1 %A A121388 _Alford Arnold_, Jul 26 2006 %E A121388 Edited, corrected and extended by _Ray Chandler_, Aug 08 2010