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 A128180 A002260 * A097807. 3
 1, -1, 2, 2, -1, 3, -2, 3, -1, 4, 3, -2, 4, -1, 5, -3, 4, -2, 5, -1, 6, 4, -3, 5, -2, 6, -1, 7, -4, 5, -3, 6, -2, 7, -1, 8, 5, -4, 6, -3, 7, -2, 8, -1, 9, -5, 6, -4, 7, -3, 8, -2, 9, -1, 10 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Row sums = A008794: (1, 1, 4, 4, 9, 9, 16, 16, ...). Unsigned row sums = the triangular sequence, A000217: (1, 3, 6, 10, ...) by virtue of the fact that each row is a permutation of the natural numbers. A128179 = A097807 * A002260. LINKS FORMULA A002260 * A097807 as infinite lower triangular matrices. From Franklin T. Adams-Watters, Apr 12 2011: (Start) T(n,k) = (2k - 1 + (-1)^(n-k)*(2n+1))/4. |T(n,k)| = (2n+1 + (-1)^(n-k)*(2k-1))/4. (End) EXAMPLE Triangle begins:    1;   -1,  2;    2, -1,  3;   -2,  3, -1,  4;    3, -2,  4, -1,  5;   -3,  4, -2,  5, -1,  6;    4, -3,  5, -2,  6, -1,  7;   ... PROG (PARI) T(n, k)=(2*k-1+(-1)^(n-k)*(2*n+1))/4 \\ Franklin T. Adams-Watters, Apr 12 2011 CROSSREFS Cf. A002260, A097807, A008794, A128179. Sequence in context: A116608 A002947 A241605 * A209279 A074754 A322529 Adjacent sequences:  A128177 A128178 A128179 * A128181 A128182 A128183 KEYWORD tabl,sign AUTHOR Gary W. Adamson, Feb 17 2007 STATUS approved

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Last modified January 17 22:33 EST 2022. Contains 350410 sequences. (Running on oeis4.)