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 A079810 Sums of diagonals (upward from left to right) of the triangle shown in A079809. 1
 1, 1, 5, 3, 8, 8, 16, 12, 21, 21, 33, 27, 40, 40, 56, 48, 65, 65, 85, 75, 96, 96, 120, 108, 133, 133, 161, 147, 176, 176, 208, 192, 225, 225, 261, 243, 280, 280, 320, 300, 341, 341, 385, 363, 408, 408, 456, 432, 481, 481, 533, 507, 560, 560, 616, 588, 645, 645 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Table of n, a(n) for n=1..58. Index entries for linear recurrences with constant coefficients, signature (1,0,0,2,-2,0,0,-1,1). FORMULA a(4k) = 3k^2. a(4k+1) = a(4k+2) = 3k^2+4k+1. a(4k+3) = 3k^2+8k+5. From Chai Wah Wu, Feb 03 2021: (Start) a(n) = a(n-1) + 2*a(n-4) - 2*a(n-5) - a(n-8) + a(n-9) for n > 9. G.f.: x*(-3*x^4 + 2*x^3 - 4*x^2 - 1)/((x - 1)^3*(x + 1)^2*(x^2 + 1)^2). (End) EXAMPLE a(7) = T(7,1)+T(6,2)+T(5,3)+T(4,4) = 7+2+3+4 = 16. CROSSREFS Cf. A079808, A079809. Cf. A079811, A092542. Sequence in context: A010484 A174930 A179452 * A300884 A337440 A092748 Adjacent sequences: A079807 A079808 A079809 * A079811 A079812 A079813 KEYWORD nonn AUTHOR Amarnath Murthy, Feb 10 2003 EXTENSIONS Edited by David Wasserman, May 11 2004 STATUS approved

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Last modified November 29 13:49 EST 2023. Contains 367445 sequences. (Running on oeis4.)