A059235 The array in A059219 read by antidiagonals in the direction in which it was constructed.

1, 0, 1, 0, 1, 2, 0, 2, 3, 5, 0, 5, 8, 12, 15, 0, 15, 27, 39, 48, 55, 0, 55, 103, 152, 190, 221, 239, 0, 239, 460, 680, 871, 1025, 1137, 1199, 0, 1199, 2336, 3471, 4493, 5374, 6062, 6553, 6810, 0, 6810, 13363, 19903, 25958, 31351, 35884, 39399, 41847, 43108, 0

Offset: 1

Author

N. J. A. Sloane, Jan 18 2001

Keywords

• easy
• nonn
• tabl
• nice

Examples

			The array begins
1 1 0 5 0 55 0 ...
0 1 3 5 48 55 ...
2 2 8 39 103 ...
0 12 27 152 ...
15 15 190 ...
0 221 ...
		

Links

• G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened
• Index entries for sequences related to boustrophedon transform

Crossrefs

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

Programs

Mathematica

max = 10; t[0, 0] = 1; t[0, ?EvenQ] = 0; t[?OddQ, 0] = 0; t[n_, k_] /; OddQ[n+k](*up*):= t[n, k] = t[n+1, k-1] + Sum[t[n, j], {j, 0, k-1}]; t[n_, k_] /; EvenQ[n+k](*down*):= t[n, k] = t[n-1, k+1] + Sum[t[j, k], {j, 0, n-1}]; Table[tn = Table[t[n-k, k], {k, 0, n}]; If[OddQ[n], tn, tn // Reverse] , {n, 0, max}] // Flatten (* Jean-François Alcover, Nov 20 2012 *)

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Jan 24 2001