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A077966 Expansion of 1/(1+2*x^2). 6
1, 0, -2, 0, 4, 0, -8, 0, 16, 0, -32, 0, 64, 0, -128, 0, 256, 0, -512, 0, 1024, 0, -2048, 0, 4096, 0, -8192, 0, 16384, 0, -32768, 0, 65536, 0, -131072, 0, 262144, 0, -524288, 0, 1048576, 0, -2097152, 0, 4194304, 0, -8388608, 0, 16777216, 0, -33554432, 0, 67108864, 0, -134217728, 0, 268435456 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Normally sequences like this are not included, since with the alternating 0's deleted it is already in the database.

Inverse binomial transform of A087455. - Philippe Deléham, Dec 02 2008

Pisano period lengths: 1, 1, 2, 1, 8, 2, 12, 1, 6, 8, 10, 2, 24, 12, 8, 1, 16, 6, 18, 8,... - R. J. Mathar, Aug 10 2012

LINKS

Table of n, a(n) for n=0..56.

Index entries for linear recurrences with constant coefficients, signature (0,-2)

FORMULA

a(n) = (1+(-1)^n)*(-2)^(n/2)/2. - R. J. Mathar, Apr 23 2009

a(n) = ((n+1) mod 2 )*(-2)^floor((n+1)/2). - Wesley Ivan Hurt, Apr 06 2014

MAPLE

A077966:=n->(1+(-1)^n)*(-2)^(n/2)/2; seq(A077966(n), n=0..50); # Wesley Ivan Hurt, Apr 02 2014

MATHEMATICA

CoefficientList[Series[1/(1 + 2*x^2), {x, 0, 200}], x] (* Vladimir Joseph Stephan Orlovsky, Jun 10 2011 *)

PROG

(Sage) [lucas_number1(n, 0, 2) for n in xrange(1, 58)] # Zerinvary Lajos, Jul 16 2008

(PARI) Vec(1/(1+2*x^2)+O(x^99)) \\ Charles R Greathouse IV, Sep 24 2012

(PARI) for(n=0, 51, print1(imag(quadgen(-8)^(n+1)), ", ")) \\ Arkadiusz Wesolowski, Dec 26 2012

CROSSREFS

Cf. A000079, A077957.

Sequence in context: A194795 A131575 A077957 * A275670 A021102 A021053

Adjacent sequences:  A077963 A077964 A077965 * A077967 A077968 A077969

KEYWORD

sign,easy

AUTHOR

N. J. A. Sloane, Nov 17 2002

STATUS

approved

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Last modified November 23 13:09 EST 2017. Contains 295127 sequences.