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A078529
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Exponent sequence for a bilinear recursive sequence.
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1
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3, 1, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 9, 10, 12, 15, 18, 21, 24, 28, 32, 36, 40, 45, 51, 55, 60, 66, 72, 78, 84, 91, 98, 105, 112, 120, 129, 136, 144, 153, 162, 171, 180, 190, 200, 210, 220, 231, 243, 253, 264, 276, 288, 300, 312, 325, 338, 351, 364, 378, 393, 406, 420
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OFFSET
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0,1
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,0,0,0,0,0,0,0,1,-2,1).
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FORMULA
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G.f.: (3 - 5*x + x^2 + x^3 + x^7 + x^11 - 2*x^12 + 3*x^13) / ((1 - x)^2 * (1 - x^12)).
a(8-n) - a(n) = -1 if n == 0 (mod 12), +1 if n == 8 (mod 12), 0 otherwise.
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EXAMPLE
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3 + x + x^7 + 2*x^8 + 3*x^9 + 4*x^10 + 6*x^11 + 9*x^12 + 10*x^13 + ...
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MATHEMATICA
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LinearRecurrence[{2, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -2, 1}, {3, 1, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 9, 10}, 70] (* Harvey P. Dale, May 27 2017 *)
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PROG
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(PARI) {a(n) = (n%12==0) + (n-4)^2\8}
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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