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A215149
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a(n) = n * (1 + 2^(n-1)).
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4
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0, 2, 6, 15, 36, 85, 198, 455, 1032, 2313, 5130, 11275, 24588, 53261, 114702, 245775, 524304, 1114129, 2359314, 4980755, 10485780, 22020117, 46137366, 96469015, 201326616, 419430425, 872415258, 1811939355, 3758096412
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OFFSET
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0,2
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COMMENTS
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Related to Bernoulli numbers.
Essentially the same as A135854.
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LINKS
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G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (6,-13,12,-4).
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FORMULA
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Discovered by a(n) = (A157809(n) - A164555(n)) / A027642(n).
a(n) = n (the nonnegative integers A001477(n)) + n*2^(n-1) (their binomial transform A001787(n)).
a(n+1) - a(n) = 2,4,9,21,... = A001792(n) + 1.
a(n+1) - 2*a(n) = 2 before A132045(n+1).
a(n) is the binomial transform of b(n) = 0,2,2,3,4,5,... = A001477(n) with 2 instead of 1. b(n) = (A164558(n) - A027641(n))/A027642(n)?
G.f. x*(2-6*x+5*x^2) / ( (2*x-1)^2*(x-1)^2 ). - R. J. Mathar, Aug 06 2012
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MATHEMATICA
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Table[n(1+2^(n-1)), {n, 0, 30}] (* or *) LinearRecurrence[{6, -13, 12, -4}, {0, 2, 6, 15}, 30] (* Harvey P. Dale, Oct 18 2013 *)
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PROG
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(PARI) a(n) = n*(1+2^(n-1)) \\ Michel Marcus, Mar 10 2013
(Magma) [n*(1 + 2^(n-1)): n in [0..30]]; // G. C. Greubel, Apr 19 2018
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CROSSREFS
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Sequence in context: A301600 A084860 A084798 * A017923 A238830 A018018
Adjacent sequences: A215146 A215147 A215148 * A215150 A215151 A215152
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KEYWORD
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nonn
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AUTHOR
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Paul Curtz, Aug 04 2012
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STATUS
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approved
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