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A123720
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a(n) = 2^n + 2^(n-1) - n.
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3
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2, 4, 9, 20, 43, 90, 185, 376, 759, 1526, 3061, 6132, 12275, 24562, 49137, 98288, 196591, 393198, 786413, 1572844, 3145707, 6291434, 12582889, 25165800, 50331623, 100663270, 201326565, 402653156, 805306339, 1610612706, 3221225441
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) = A007283(n-1) - n.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..1000
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FORMULA
| O.g.f.: x(2-4x+3x^2)/((1-x)^2*(1-2x)). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 08 2008
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MATHEMATICA
| lst={}; Do[AppendTo[lst, 2^n+2^(n-1)-n], {n, 5!}]; lst ...and/or... s=2; lst={s}; Do[s+=s+n++; AppendTo[lst, s], {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 25 2008]
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PROG
| (PARI) for(n=1, 31, print1(2^n+2^(n-1)-n, ", "))
(MAGMA) [2^n + 2^(n-1) - n: n in [1..40] ]; // Vincenzo Librandi, May 18 2011
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CROSSREFS
| Cf. A007283.
Sequence in context: A018103 A175104 * A179744 A034007 A109975 A129891
Adjacent sequences: A123717 A123718 A123719 * A123721 A123722 A123723
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KEYWORD
| nonn
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 09 2006
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