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A087211 a(n) = floor((1+2^n+3^n)/3). 1
1, 2, 4, 12, 32, 92, 264, 772, 2272, 6732, 20024, 59732, 178512, 534172, 1599784, 4793892, 14370752, 43090412, 129227544, 387595252, 1162610992, 3487483452, 10461751304, 31383855812, 94148771232, 282440721292, 847310979064 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
LINKS
FORMULA
G.f.: (1-2*x-3*x^2+4*x^3)/((1+x)*(1-2*x)*(1-3*x));
E.g.f.: (exp(3*x)+exp(2*x)+2*exp(0)-exp(-x))/3;
a(n) = (3^n+2^n+2*0^n-(-1)^n)/3.
a(n) = 2*A094039(n), n>0. - R. J. Mathar, Feb 13 2015
a(n) = 4*a(n-1) - a(n-2) - 6*a(n-3). - Wesley Ivan Hurt, Apr 25 2023
MATHEMATICA
Table[Floor[(1+2^n+3^n)/3], {n, 0, 30}] (* or *) LinearRecurrence[{4, -1, -6}, {1, 2, 4, 12}, 30] (* Harvey P. Dale, May 21 2018 *)
CROSSREFS
Sequence in context: A026151 A025178 A231295 * A161177 A039721 A148193
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Aug 26 2003
STATUS
approved

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Last modified June 24 01:53 EDT 2024. Contains 373661 sequences. (Running on oeis4.)