A059237 Variation of Boustrophedon transform described in A059219 applied to sequence 0,1,0,0,0,....

0, 1, 2, 5, 16, 59, 258, 1296, 7362, 46609, 325147, 2477212, 20460278, 182076531, 1736623109, 17672266151, 191111489038, 2188592796698, 26458831601847, 336735773968857, 4500142285227330, 63007188219787855, 922312862937555109

Offset: 0

Author

N. J. A. Sloane, Jan 20 2001

Keywords

• nonn

Links

• Index entries for sequences related to boustrophedon transform

Crossrefs

Cf. A000667, A059216, A059217, A059220, A059219.

Programs

Maple

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)