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 A226203 a(5n) = a(5n+3) = a(5n+4) = 2n+1, a(5n+1) = 2n-3, a(5n+2) = 2n-1. 2
 1, -3, -1, 1, 1, 3, -1, 1, 3, 3, 5, 1, 3, 5, 5, 7, 3, 5, 7, 7, 9, 5, 7, 9, 9, 11, 7, 9, 11, 11, 13, 9, 11, 13, 13, 15, 11, 13, 15, 15, 17, 13, 15, 17, 17, 19, 15, 17, 19, 19, 21, 17, 19, 21, 21, 23, 19, 21, 23, 23, 25, 21, 23, 25, 25 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Given the numerators of A225948/A226008 ordered according to A226096: 0, -15, -3, 2, 3, 6, -7, 5, 12, 15, 20, 9, 21, 30, 35,... = t(n), then (a(n) + t(n)/a(n))^2 =  A226096(n). First six differences (of period 5): ...-4,   2,   2,   0,   2,  -4,   2,   2,   0,   2, ... ....6,   0,  -2,   2,  -6,   6,   0,  -2,   2,  -6, ... ...-6,  -2,   4,  -8,  12,  -6,  -2,   4,  -8,  12, ... ....4,   6, -12,  20, -18,   4,   6, -12,  20, -18, ... ....2, -18,  32, -38,  22,   2, -18,  32, -38,  22, ... ..-20,  50, -70,  60, -20, -20,  50, -70,  60, -20, ... LINKS Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1). FORMULA a(n+5) = a(n) + 2. G.f.: (1-4*x+2*x^2+2*x^3+x^5)/((1-x)^2*(1+x+x^2+x^3+x^4)). [Bruno Berselli, Jun 01 2013] a(n) = a(n-1)+a(n-5)-a(n-6) with a(0)=a(3)=a(4)=1, a(1)=-3, a(2)=-1, a(5)=3. [Bruno Berselli, Jun 01 2013] MATHEMATICA a[n_] := 2 Quotient[n, 5] + Switch[Mod[n, 5], 0, 1, 1, -3, 2, -1, 3, 1, 4, 1]; Table[a[n], {n, 0, 64}] (* Jean-François Alcover, Jun 22 2017 *) PROG (Haskell) import Data.List (transpose) a226203 n = a226203_list !! n a226203_list = concat \$ transpose                [[1, 3 ..], [-3, -1 ..], [-1, 1 ..], [1, 3 ..], [1, 3 ..]] -- Reinhard Zumkeller, Jun 02 2013 CROSSREFS Cf. A007395, A005408, A130497, A226096. Sequence in context: A087612 A260626 A155828 * A327791 A051997 A155744 Adjacent sequences:  A226200 A226201 A226202 * A226204 A226205 A226206 KEYWORD sign,easy AUTHOR Paul Curtz, May 31 2013 EXTENSIONS Edited by Bruno Berselli, Jun 01 2013 STATUS approved

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Last modified October 22 01:46 EDT 2020. Contains 337948 sequences. (Running on oeis4.)