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A154327
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Diagonal sums of number triangle A132046.
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2
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1, 1, 2, 5, 8, 15, 24, 41, 66, 109, 176, 287, 464, 753, 1218, 1973, 3192, 5167, 8360, 13529, 21890, 35421, 57312, 92735, 150048, 242785, 392834, 635621, 1028456, 1664079, 2692536, 4356617, 7049154, 11405773, 18454928, 29860703, 48315632, 78176337, 126491970, 204668309, 331160280, 535828591, 866988872
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: (1 - x^2 + 2x^3 + x^4)/( (1-x^2)*(1-x-x^2) ).
a(n) = 0^n - (3 + (-1)^n)/2 + 2*Fibonacci(n+1).
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MATHEMATICA
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Join[{1}, LinearRecurrence[{1, 2, -1, -1}, {1, 2, 5, 8}, 25]] (* G. C. Greubel, Sep 11 2016 *)
CoefficientList[Series[(1 - x^2 + 2 x^3 + x^4) / ((1 - x^2) (1 - x - x^2)), {x, 0, 50}], x] (* Vincenzo Librandi, Sep 12 2016 *)
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PROG
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(Magma) [0^n-(3+(-1)^n)/2+2*Fibonacci(n+1):n in [0..40]]; // Vincenzo Librandi, Sep 12 2016
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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