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A048509
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a(n) = T(4,n), array T given by A048505.
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3
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1, 26, 87, 233, 577, 1377, 3217, 7409, 16881, 38129, 85489, 190449, 421873, 929777, 2039793, 4456433, 9699313, 21037041, 45481969, 98041841, 210763761, 451936241, 966787057, 2063597553, 4395630577, 9344909297, 19830669297, 42010148849, 88852135921
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OFFSET
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0,2
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COMMENTS
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n-th difference of a(n), a(n-1), ..., a(0) is (25, 36, 49, 64, 81...).
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LINKS
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FORMULA
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a(n) = (n^2+17*n+64) * 2^(n-2) - 15. - Ralf Stephan, Feb 05 2004
a(n) = 7*a(n-1)-18*a(n-2)+20*a(n-3)-8*a(n-4). - Colin Barker, Mar 04 2015
G.f.: (72*x^3-77*x^2+19*x+1) / ((x-1)*(2*x-1)^3). - Colin Barker, Mar 04 2015
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MATHEMATICA
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LinearRecurrence[{7, -18, 20, -8}, {1, 26, 87, 233}, 30] (* Harvey P. Dale, Jul 08 2023 *)
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PROG
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(Magma) [(n^2+17*n+64) * 2^(n-2) - 15: n in [0..30]]; // Vincenzo Librandi, Sep 26 2011
(PARI) Vec((72*x^3-77*x^2+19*x+1)/((x-1)*(2*x-1)^3) + O(x^100)) \\ Colin Barker, Mar 04 2015
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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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