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A081660
n+A001045(n+1).
2
1, 2, 5, 8, 15, 26, 49, 92, 179, 350, 693, 1376, 2743, 5474, 10937, 21860, 43707, 87398, 174781, 349544, 699071, 1398122, 2796225, 5592428, 11184835, 22369646, 44739269, 89478512, 178956999, 357913970, 715827913, 1431655796, 2863311563
OFFSET
0,2
FORMULA
a(n) = 2^(n+1)/3+n+(-1)^n/3.
G.f.: (1-x-2*x^3)/((1+x)*(1-2*x)*(1-x)^2). [Bruno Berselli, Aug 11 2013]
MATHEMATICA
Table[2^(n + 1)/3 + n + (-1)^n/3, {n, 0, 40}] (* Vincenzo Librandi, Aug 10 2013 *)
PROG
(Magma) [2^(n+1)/3+n+(-1)^n/3: n in [0..40]]; // Vincenzo Librandi, Aug 10 2013
CROSSREFS
Sequence in context: A074027 A018156 A051293 * A285291 A065618 A257548
KEYWORD
nonn,easy
AUTHOR
Paul Barry, Mar 26 2003
STATUS
approved