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 A110681 A convolution triangle of numbers based on A071356. 1
 1, 2, 1, 6, 4, 1, 20, 16, 6, 1, 72, 64, 30, 8, 1, 272, 260, 140, 48, 10, 1, 1064, 1072, 636, 256, 70, 12, 1, 4272, 4480, 2856, 1288, 420, 96, 14, 1, 17504, 18944, 12768, 6272, 2320, 640, 126, 16, 1, 72896, 80928, 57024, 29952, 12192, 3852, 924, 160, 18, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Michael De Vlieger, Table of n, a(n) for n = 0..11324 (rows 0 <= n <= 150). G. Kreweras, Sur les hiérarchies de segments, Cahiers du Bureau Universitaire de Recherche Opérationnelle, Institut de Statistique, Université de Paris, #20 (1973), p. 32-33. G. Kreweras, Sur les hiérarchies de segments, Cahiers du Bureau Universitaire de Recherche Opérationnelle, Institut de Statistique, Université de Paris, #20 (1973). (Annotated scanned copy) FORMULA T(0, 0) = 1; T(n, k) = 0 if k<0 or if k>n; T(n, k) = T(n-1, k-1) + 2*T(n-1, k) + 2*T(n-1, k+1). Sum_{k, k>=0} T(m, k)*T(n, k)*2^k = T(m+n, 0) = A071356(m+n). Sum_{k, k>=0} T(n, k)*(2^(k+1) - 1) = 5^n. Sum_{k, k>=0} (-1)^(n-k)*T(n, k)*(2^(k+1) - 1) = 1. EXAMPLE Triangle starts:    1;    2,  1;    6,  4,  1;   20, 16,  6,  1;   72, 64, 30,  8,  1;   ... MATHEMATICA T[n_, k_] := T[n, k] = Which[n == k == 0, 1, n == 0, 0, k == 0, 0, k > n, 0, True, T[n - 1, k - 1] + 2 T[n - 1, k] + 2 T[n - 1, k + 1]]; Table[T[n, k], {n, 0, 10}, {k, n}] // Flatten (* Michael De Vlieger, Nov 05 2017 *) CROSSREFS Cf. A071356 (1st column), A071357 (2nd column). Cf. A052705 (diagonal sums), A001003 (row sums). Sequence in context: A125693 A094527 A054335 * A117852 A080245 A080247 Adjacent sequences:  A110678 A110679 A110680 * A110682 A110683 A110684 KEYWORD nonn,tabl AUTHOR Philippe Deléham, Sep 14 2005 STATUS approved

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Last modified December 16 00:33 EST 2019. Contains 330013 sequences. (Running on oeis4.)