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A133140 a(0) = 2, a(n) = 2^n + 2 for n>=1. 3
2, 4, 6, 10, 18, 34, 66, 130, 258, 514, 1026, 2050, 4098, 8194, 16386, 32770, 65538, 131074, 262146, 524290, 1048578, 2097154, 4194306, 8388610, 16777218, 33554434, 67108866, 134217730, 268435458, 536870914, 1073741826, 2147483650, 4294967298 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Sum of the coefficients of the polynomial Q(n,x)=(1+x)[(1+x)^(n-1)+x^(n-1)], Q(0,x)=2.

Also row sums of A133138. - R. J. Mathar, Jun 12 2008

LINKS

Table of n, a(n) for n=0..32.

FORMULA

a(n)=2*A094373(n). a(n)=A052548(n), n>0. - R. J. Mathar, Jun 12 2008

MATHEMATICA

Table[If[n < 2, 2, 1] + Total[Table[Coefficient[Expand[(1 + x) ((1 + x)^(n - 1) + x^(n - 1))], x^m], {m, 1, n}]], {n, 0, 22}] (* Mats Granvik, May 19 2012 *)

Join[{2}, 2^Range[40]+2] (* Harvey P. Dale, Aug 16 2014 *)

CROSSREFS

Sequence in context: A018074 A288465 A000067 * A026680 A317639 A164141

Adjacent sequences:  A133137 A133138 A133139 * A133141 A133142 A133143

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Sep 21 2007

EXTENSIONS

Edited by R. J. Mathar, Jun 12 2008

STATUS

approved

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Last modified October 17 02:02 EDT 2018. Contains 316275 sequences. (Running on oeis4.)