A059220 The array in A059219 read by antidiagonals in 'up' direction.

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

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, A059235.

Programs

Maple

See A059219 for Maple code.

Mathematica

max = 9; 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[t[n - k, k], {n, 0, max}, {k, 0, n}] // Flatten (* Jean-François Alcover, Aug 19 2013 *)

Extensions

More terms from Floor van Lamoen, Jan 19 2001