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 A059237 #6 Mar 30 2012 16:48:58 %S A059237 0,1,2,5,16,59,258,1296,7362,46609,325147,2477212,20460278,182076531, %T A059237 1736623109,17672266151,191111489038,2188592796698,26458831601847, %U A059237 336735773968857,4500142285227330,63007188219787855,922312862937555109 %N A059237 Variation of Boustrophedon transform described in A059219 applied to sequence 0,1,0,0,0,.... %H A059237 <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a> %p A059237 aaa := proc(m,n) option remember; local i,j,r,s,t1; if m=0 and n=0 then RETURN(0); fi; if m=1 and n=0 then RETURN(1); fi; if n = 0 and m mod 2 = 1 then RETURN(0); fi; if m = 0 and n mod 2 = 0 then RETURN(0); fi; s := m+n; if s mod 2 = 1 then t1 := aaa(m+1,n-1); for j from 0 to n-1 do t1 := t1+aaa(m,j); od: else t1 := aaa(m-1,n+1); for j from 0 to m-1 do t1 := t1+aaa(j,n); od: fi; RETURN(t1); end; # the n-th antidiagonal in the up direction is aaa(n,0), aaa(n-1,1), aaa(n-2,2), ..., aaa(0,n) %Y A059237 Cf. A000667, A059216, A059217, A059220, A059219. %K A059237 nonn %O A059237 0,3 %A A059237 _N. J. A. Sloane_, Jan 20 2001