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0, 0, 2, 2, 4, 8, 14, 26, 48, 88, 162, 298, 548, 1008, 1854, 3410, 6272, 11536, 21218, 39026, 71780, 132024, 242830, 446634, 821488, 1510952, 2779074, 5111514, 9401540, 17292128, 31805182, 58498850, 107596160, 197900192, 363995202, 669491554
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OFFSET
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0,3
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COMMENTS
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Number of anti-palindromic compositions of n+1 of even length.
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LINKS
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George E. Andrews, Matthew Just, and Greg Simay, Anti-palindromic compositions, arXiv:2102.01613 [math.CO], 2021. Also Fib. Q., 60:2 (2022), 164-176. See Table 1.
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FORMULA
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a(n) = a(n-1) + a(n-2) + a(n-3) for n > 2.
G.f.: -2*x^2/(x^3 + x^2 + x - 1). (End)
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MATHEMATICA
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LinearRecurrence[{1, 1, 1}, {0, 0, 2}, 50] (* Paolo Xausa, May 27 2024 *)
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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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