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 A059513 #4 Mar 02 2015 16:08:45 %S A059513 1,2,6,23,116,736,5659,50796,521040,6006587,76874524,1081439062, %T A059513 16586149365,275442822510,4924040788654 %N A059513 Variation of Boustrophedon transform applied to 1,1,1,1,... Fill an array by diagonals, in alternating directions. The first entry is 1 each time. For the next element of a diagonal, add to the previous element the elements of the row and the column the new element is in. The final element of each diagonal gives a(n). %e A059513 The array begins %e A059513 1 ....2 ...1 ..23 ..1 ... %e A059513 1 ....4 ..19 ..48 ... %e A059513 6 ...13 ..87 ... %e A059513 1 ..107 ... %e A059513 116 ... %e A059513 1 ... %Y A059513 Cf. A000667, A035002, A059216, A059219, A059575, A059574. %K A059513 easy,nonn %O A059513 1,2 %A A059513 _Floor van Lamoen_, Jan 23 2001