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A176691
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a(n) = 2^n + 2*n + 1.
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11
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2, 5, 9, 15, 25, 43, 77, 143, 273, 531, 1045, 2071, 4121, 8219, 16413, 32799, 65569, 131107, 262181, 524327, 1048617, 2097195, 4194349, 8388655, 16777265, 33554483, 67108917, 134217783, 268435513, 536870971, 1073741885, 2147483711, 4294967361, 8589934659, 17179869253
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OFFSET
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0,1
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COMMENTS
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The subsequence of primes in this sequence is A163115.
Also the number of connected dominating sets in the (n+1)-wheel graph. - Eric W. Weisstein, Aug 30 2017
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LINKS
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FORMULA
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a(n) = 4*a(n-1) - 5*a(n-2) + 2*a(n-3).
G.f.: (-2 + 3*x + x^2)/((2*x - 1)*(x - 1)^2). (End)
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MAPLE
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MATHEMATICA
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CoefficientList[Series[(-2 + 3 x + x^2)/((-1 + x)^2 (-1 + 2 x)), {x, 0, 20}], x] (* Eric W. Weisstein, Aug 30 2017 *)
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PROG
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(PARI) vector(40, n, n--; 2^n + 2*n + 1) \\ Michel Marcus, Aug 12 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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EXTENSIONS
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Corrected (one 1048617 replaced by 2097195) by R. J. Mathar, Apr 28 2010
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STATUS
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approved
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