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A187893
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a(0)=1, a(1)=4, a(n) = a(n-1) + a(n-2) - 1.
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1
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1, 4, 4, 7, 10, 16, 25, 40, 64, 103, 166, 268, 433, 700, 1132, 1831, 2962, 4792, 7753, 12544, 20296, 32839, 53134, 85972, 139105, 225076, 364180, 589255, 953434, 1542688, 2496121, 4038808, 6534928, 10573735, 17108662, 27682396, 44791057, 72473452, 117264508
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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. -x*(-1-2*x+4*x^2) / ( (x-1)*(x^2+x-1) ). - R. J. Mathar, Mar 15 2011
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MATHEMATICA
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Join[{a=1, b=4}, Table[c=a+b-1; a=b; b=c, {n, 100}]]
LinearRecurrence[{2, 0, -1}, {1, 4, 4}, 40] (* Harvey P. Dale, Jun 06 2020 *)
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PROG
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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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