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
Examples
Triangle begins: 1; 0, 1; 0, 0, 1; 1, 1, 1, 0; 3, 2, 1, 0, 0; 0, 3, 5, 6, 6, 6; ...
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
Programs
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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
Extensions
More terms from Larry Reeves (larryr(AT)acm.org), Dec 12 2000
Comments