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A226315
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(n^2/8+3*n/8-2)*2^n+3.
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1
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0, 0, 5, 27, 99, 307, 867, 2307, 5891, 14595, 35331, 83971, 196611, 454659, 1040387, 2359299, 5308419, 11862019, 26345475, 58195971, 127926275, 279969795, 610271235, 1325400067, 2868903939, 6190792707, 13321109507, 28588376067, 61203283971, 130728067075, 278636003331, 592705486851, 1258425417731
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OFFSET
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1,3
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LINKS
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FORMULA
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MATHEMATICA
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Table[(n^2 / 8 + 3 n / 8 - 2) 2^n + 3, {n, 40}] (* or *) CoefficientList[Series[x^2 (5 - 8 x) / ((1 - x) (1 - 2 x)^3), {x, 0, 40}], x] (* Vincenzo Librandi, Jun 18 2013 *)
LinearRecurrence[{7, -18, 20, -8}, {0, 0, 5, 27}, 40] (* Harvey P. Dale, Jul 10 2018 *)
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PROG
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(Magma) [(n^2/8+3*n/8-2)*2^n+3: n in [1..35]] /* or */ I:=[0, 0, 5, 27]; [n le 4 select I[n] else 7*Self(n-1)-18*Self(n-2)+20*Self(n-3)-8*Self(n-4): n in [1..40]]; // Vincenzo Librandi, Jun 18 2013
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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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