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A343539
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a(n) = (2*n+1)*Lucas(2*n+1).
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1
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1, 12, 55, 203, 684, 2189, 6773, 20460, 60707, 177631, 513996, 1473817, 4194025, 11858508, 33345679, 93320819, 260079468, 722163365, 1998685277, 5515470636, 15180186491, 41680890247, 114197428620, 312260427313, 852296004049, 2322415005324, 6318599122663, 17166545274395
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: (1-x)*(1 + 7*x + x^2)/(1 - 3*x + x^2)^2.
a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3) - a(n-4). - Wesley Ivan Hurt, Apr 19 2021
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MATHEMATICA
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PROG
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(PARI) a(n) = (2*n+1)*(fibonacci(2*n+2)+fibonacci(2*n)) \\ Andrew Howroyd, Jan 01 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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