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A024037
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a(n) = 4^n - n.
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15
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1, 3, 14, 61, 252, 1019, 4090, 16377, 65528, 262135, 1048566, 4194293, 16777204, 67108851, 268435442, 1073741809, 4294967280, 17179869167, 68719476718, 274877906925, 1099511627756
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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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MATHEMATICA
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Table[4^n - n, {n, 0, 30}] (* or *) CoefficientList[Series[(1 - 3 x + 5 x^2) / ((1 - 4 x) (1 - x)^2), {x, 0, 30}], x] (* Vincenzo Librandi, Jun 16 2013 *)
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PROG
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(Magma) I:=[1, 3, 14]; [n le 3 select I[n] else 6*Self(n-1)-9*Self(n-2)+4*Self(n-3): n in [1..30]]; // Vincenzo Librandi, Jun 16 2013
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CROSSREFS
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Cf. numbers of the form k^n-n: A000325 (k=2), A024024 (k=3), this sequence (k=4), A024050 (k=5), A024063 (k=6), A024076 (k=7), A024089 (k=8), A024102 (k=9), A024115 (k=10), A024128 (k=11), A024141 (k=12).
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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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