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A005126 2^n + n + 1.
(Formerly M1061)
11
2, 4, 7, 12, 21, 38, 71, 136, 265, 522, 1035, 2060, 4109, 8206, 16399, 32784, 65553, 131090, 262163, 524308, 1048597, 2097174, 4194327, 8388632, 16777241, 33554458, 67108891, 134217756, 268435485, 536870942, 1073741855, 2147483680, 4294967329, 8589934626 (list; graph; refs; listen; history; internal format)
OFFSET

0,1

COMMENTS

Binomial transform of (1, 1, 1, 0, 1, 0, 1, 0, 1,...). - Gary W. Adamson, Jul 20 2007

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..2000

S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 921

Index to sequences with linear recurrences with constant coefficients, signature (4,-5,2).

FORMULA

G.f.: (2-4*x+x^2)/((1-2*x)*(1-x)^2). [From S. Plouffe]

MAPLE

A005126:=-(2-4*z+z**2)/(2*z-1)/(z-1)**2; [Conjectured by S. Plouffe in his 1992 dissertation.]

g:=z/(1-2*z): gser:=series(g, z=0, 43): seq(coeff(gser, z, n)+n, n=1..34); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jan 11 2009]

MATHEMATICA

s=2; lst={s}; Do[s+=(s-n); AppendTo[lst, Abs[s]], {n, 0, 5!}]; lst [From Vladimir Orlovsky, Oct 10 2008]

PROG

(MAGMA) [2^n+n+1: n in [0..40]]; // Vincenzo Librandi, Oct 22 2011

CROSSREFS

Essentially the same as row sums of A128715.

Cf. A194455.

Sequence in context: A054161 A023433 A190168 * A054151 A018176 A135460

Adjacent sequences:  A005123 A005124 A005125 * A005127 A005128 A005129

KEYWORD

nonn,easy

AUTHOR

C. L. Mallows (colinm(AT)research.avayalabs.com)

EXTENSIONS

More terms from N. J. A. Sloane (njas(AT)research.att.com), Sep 28 2007

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Last modified February 15 08:20 EST 2012. Contains 205729 sequences.