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 A084935 #3 Mar 30 2012 18:57:05 %S A084935 0,1,2,5,7,11,15,21,25,32,39,48,54,65,73,86,94,109,119,134,145,164, %T A084935 176,194,208,228,243,265,282,305,321,348,366,392,411,440,460,491,513, %U A084935 545,566,599,624,660,683,721,747,785,812,852,881,921,950,995,1025,1070,1101 %N A084935 Diagonal sums of the array T in A084934. %e A084935 The northwest corner of T includes %e A084935 0 1 1 2 %e A084935 0 1 2 %e A084935 0 1 %e A084935 0, %e A084935 from which the first four diagonals sums are 0,1,2,5. %Y A084935 Cf. A084934. %K A084935 nonn %O A084935 1,3 %A A084935 _Clark Kimberling_, Jun 12 2003