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 A174358 #5 Apr 13 2013 08:27:31 %S A174358 5,1,25,11,35,77,7,55,49,121,17,65,119,143,221,13,85,91,181,109,289, %T A174358 23,95,161,209,299,323,437,19,115,133,253,247,391,361,529,29,125,203, %U A174358 275,377,425,551,575,725,25,145,175,319,325,493,475,667,625,841,35,185,245 %N A174358 Alternating triangle (version 3) read by rows: numbers k such that k=6*m+3-+2=r*j , r>=j and n>=q where r=6*n+3-2 or r=6*n+3+2 and j=6*q+3-2 or j=6*q+3+2. %C A174358 Numbers of form 6*m+3+2 are in even rows, numbers of form 6*m+3-2 are in odd rows. Numbers of alternating triangle (version 1) are A173865. Numbers of alternating triangle (version 2) are A174027. %e A174358 Triangle begins: 5*1 1*1 5*5 11*1 7*5 11*7 7*1 11*5 7*7 11*11 17*1 13*5 17*7 13*11 17*13 13*1 17*5 13*7 17*11 13*13 17*17.. or 5(in even 0 row) 1 25(in odd 1 row) 11 35 77(in even 2 row) 7 55 49 121(in odd 3 row) 17 65 119 143 221(in even 4 row) 13 85 91 181 169 289(in odd 5 row).. %e A174358 That is: %e A174358 5; %e A174358 1, 25; %e A174358 11, 35, 77; %e A174358 7, 55, 49, 121; %e A174358 17, 65, 119, 143; %Y A174358 Cf. A007310, A173825, A173865, A174027. %K A174358 nonn,tabl %O A174358 1,1 %A A174358 _Juri-Stepan Gerasimov_, Mar 17 2010, Mar 30 2010