A058257 Triangle read by rows: this is a variant of A008280 in which 2 rows go from left to right, 2 from right to left, 2 from left to right, etc.

1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 3, 2, 1, 0, 0, 0, 3, 5, 6, 6, 6, 0, 0, 3, 8, 14, 20, 26, 71, 71, 71, 68, 60, 46, 26, 0, 413, 342, 271, 200, 132, 72, 26, 0, 0, 0, 413, 755, 1026, 1226, 1358, 1430, 1456, 1456, 1456, 0, 0, 413, 1168, 2194, 3420, 4778, 6208, 7664, 9120, 10576

Offset

0,11

Comments

Suggested by Atkinson article in Information Processing Letters.

References

M. D. Atkinson, Partial orders and comparison problems, Sixteenth Southeastern Conference on Combinatorics, Graph Theory and Computing, (Boca Raton, Feb 1985), Congressus Numerantium 47, 77-88.

Links

Reinhard Zumkeller, Rows n = 0..120 of triangle, flattened

M. D. Atkinson, Zigzag permutations and comparisons of adjacent elements, Information Processing Letters 21 (1985), 187-189.

J. Millar, N. J. A. Sloane and N. E. Young, A new operation on sequences: the Boustrophedon transform, J. Combin. Theory, 17A (1996), 44-54 (Abstract, pdf, ps).

Index entries for sequences related to boustrophedon transform

Example

Triangle begins:
  1;
  0, 1;
  0, 0, 1;
  1, 1, 1, 0;
  3, 2, 1, 0, 0;
  0, 3, 5, 6, 6, 6;
  ...

Prog

(Haskell)
a058257 n k = a058257_tabl !! n !! k
a058257_row n = a058257_tabl !! n
a058257_tabl = [1] : ox 0 [1] where
   ox turn xs = ys : ox (mod (turn + 1) 4) ys
      where ys | turn <= 1 = scanl (+) 0 xs
               | otherwise = reverse $ scanl (+) 0 $ reverse xs
-- Reinhard Zumkeller, Nov 01 2013

Crossrefs

Cf. A058258, A008280, A000111.

Sequence in context: A321518 A267883 A333437 * A330959 A083199 A327187

Adjacent sequences: A058254 A058255 A058256 * A058258 A058259 A058260

Keyword

nonn,easy,tabl,nice

Author

N. J. A. Sloane, Dec 06 2000

Extensions

More terms from Larry Reeves (larryr(AT)acm.org), Dec 12 2000

Status

approved