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 A284418 Number of self-avoiding planar walks of length n*(n+1)/2 starting at (0,0), ending at (n,0), remaining in the first quadrant and using steps (0,1), (1,0), (1,1), (-1,1), and (1,-1) with the restriction that (0,1) is never used below the diagonal and (1,0) is never used above the diagonal. 3
 1, 1, 1, 7, 10, 31, 69, 196, 451, 1168, 2813, 7119, 17618, 44206, 111399, 277972, 709411, 1763795, 4543873, 11269489, 29244239, 72402587, 188977618, 467258134, 1225383748, 3026799348, 7969173506, 19669004793, 51959167749, 128161003199, 339530403506 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Alois P. Heinz, Animation of a(6)=69 walks Wikipedia, Lattice path Wikipedia, Self-avoiding walk FORMULA a(n) = A284414(n,n*(n+1)/2). CROSSREFS Cf. A000217, A284414. Sequence in context: A070422 A102574 A317797 * A244165 A119169 A095756 Adjacent sequences:  A284415 A284416 A284417 * A284419 A284420 A284421 KEYWORD nonn,walk AUTHOR Alois P. Heinz, Mar 26 2017 STATUS approved

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Last modified August 11 09:47 EDT 2020. Contains 336423 sequences. (Running on oeis4.)