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18, 972, 26244, 524880, 8857350, 133923132, 1874923848, 24794911296, 313810596090, 3835462841100, 45565298552268, 528708092292432, 6014054549826414, 67257769817585340, 741208075540736400
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = 36*a(n-1)-486*a(n-2)+2916*a(n-3)-6561*a(n-4). - Vincenzo Librandi, Feb 12 2013
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MATHEMATICA
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LinearRecurrence[{36, -486, 2916, -6561}, {18, 972, 26244, 524880}, 30] (* Vincenzo Librandi, Feb 12 2013 *)
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PROG
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(Magma) [(n^3+n^2)*9^n: n in [1..25]]; /* or */ I:=[18, 972, 26244, 524880]; [n le 4 select I[n] else 36*Self(n-1)-486*Self(n-2)+2916*Self(n-3)-6561*Self(n-4): n in [1..25]]; // Vincenzo Librandi, Feb 12 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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