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

1,4

Links

G. C. Greubel, Table of n, a(n) for the first 50 rows, flattened

Index entries for sequences related to boustrophedon transform

Example

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 ...

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 *)

Crossrefs

Cf. A000667, A059216, A059219, A059217, A059235.

Sequence in context: A261118 A063181 A247310 * A261630 A301503 A059431

Adjacent sequences: A059217 A059218 A059219 * A059221 A059222 A059223

Keyword

easy,nonn,tabl,nice

Author

N. J. A. Sloane, Jan 18 2001

Extensions

More terms from Floor van Lamoen, Jan 19 2001

Status

approved