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A174836 a(n) = 1 + ((6*n-1)*2^n + (-1)^n)/3. 0
1, 4, 16, 46, 124, 310, 748, 1750, 4012, 9046, 20140, 44374, 96940, 210262, 453292, 972118, 2075308, 4412758, 9349804, 19748182, 41593516, 87381334, 183151276, 383079766, 799713964, 1666536790, 3467291308, 7203018070, 14942907052, 30959555926, 64066595500, 132428158294 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
G.f.: 1/(1-x) + 1/(3*(1+x)) - 1/(3*(1-2*x)) + 8*x/(1-2*x)^2. [Richard Choulet, Apr 04 2010]
a(n) = 3*A113861(n+1) + 1. - Michel Marcus, Feb 05 2019
PROG
(PARI) a(n) = 1 + ((6*n-1)*2^n+(-1)^n)/3; \\ Michel Marcus, Feb 05 2019
CROSSREFS
Cf. A113861.
Sequence in context: A007315 A055342 A213292 * A244252 A369401 A308592
KEYWORD
nonn,easy
AUTHOR
Fernando J. Ballesteros (fernando.ballesteros(AT)uv.es), Mar 30 2010
EXTENSIONS
More terms from Michel Marcus, Feb 05 2019
STATUS
approved

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Last modified March 29 11:45 EDT 2024. Contains 371278 sequences. (Running on oeis4.)