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A087211 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

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-1,-6).

FORMULA

G.f.: (1-2x-3x^2+4x^3)/((1+x)(1-2x)(1-3x));

E.g.f.: (exp(3x)+exp(2x)+2exp(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

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

Cf. A011782.

Sequence in context: A026151 A025178 A231295 * A161177 A039721 A148193

Adjacent sequences:  A087208 A087209 A087210 * A087212 A087213 A087214

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Aug 26 2003

STATUS

approved

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Last modified August 25 03:10 EDT 2019. Contains 326318 sequences. (Running on oeis4.)