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A107684 Union of sequences 2^k-1, 2^k and 2^k+1. 2
0, 1, 2, 3, 4, 5, 7, 8, 9, 15, 16, 17, 31, 32, 33, 63, 64, 65, 127, 128, 129, 255, 256, 257, 511, 512, 513, 1023, 1024, 1025, 2047, 2048, 2049, 4095, 4096, 4097, 8191, 8192, 8193, 16383, 16384, 16385, 32767, 32768, 32769, 65535, 65536, 65537, 131071 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Subsequence of A107686.

LINKS

Table of n, a(n) for n=0..48.

Index entries for linear recurrences with constant coefficients, signature (-1,-1,2,2,2).

FORMULA

a(n) = if n<=2 then n else 2^(floor(n/3)+1) + n mod 3 - 1. - Reinhard Zumkeller, Jun 05 2005

G.f.:-x*(1+3*x+6*x^2+7*x^3+6*x^4+4*x^5+2*x^6)/((2*x^3-1)*(x^2+x+1)) [From Maksym Voznyy (voznyy(AT)mail.ru), Aug 12 2009]

MATHEMATICA

Flatten[{#-1, #, #+1}&/@(2^Range[0, 20])]//Union (* Harvey P. Dale, Oct 06 2017 *)

CROSSREFS

Cf. A000225, A000079, A000051.

Sequence in context: A201816 A155900 A274949 * A111796 A039124 A056759

Adjacent sequences:  A107681 A107682 A107683 * A107685 A107686 A107687

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, May 20 2005

EXTENSIONS

Description corrected by Henrik Lundquist, Jun 06 2005

STATUS

approved

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Last modified June 5 16:19 EDT 2020. Contains 334852 sequences. (Running on oeis4.)