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A102561 a(n) = 2^floor(n/2)*((-1)^floor(n/2) + (-1)^n)/2. 1
1, 0, 0, -2, 4, 0, 0, -8, 16, 0, 0, -32, 64, 0, 0, -128, 256, 0, 0, -512, 1024, 0, 0, -2048, 4096, 0, 0, -8192, 16384, 0, 0, -32768, 65536, 0, 0, -131072, 262144, 0, 0, -524288, 1048576, 0, 0, -2097152, 4194304, 0, 0, -8388608, 16777216, 0, 0, -33554432, 67108864, 0, 0, -134217728 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Table of n, a(n) for n=0..55.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,4).

FORMULA

a(n) = ((-2)^floor(n/2) + (-1)^n*2^floor(n/2))/2.

a(n) = A102560(n)*2^floor(n/2).

a(n) = 4*a(n-4). - Georg Fischer, Sep 02 2021

MATHEMATICA

LinearRecurrence[{0, 0, 0, 4}, {1, 0, 0, -2}, 64] (* Georg Fischer, Sep 02 2021 *)

PROG

Cf. A102560.

CROSSREFS

Sequence in context: A213672 A309244 A004025 * A072068 A078145 A348892

Adjacent sequences:  A102558 A102559 A102560 * A102562 A102563 A102564

KEYWORD

easy,sign

AUTHOR

Paul Barry, Jan 14 2005

STATUS

approved

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Last modified September 26 08:43 EDT 2022. Contains 356993 sequences. (Running on oeis4.)