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A102561 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.

FORMULA

a(n)=((-2)^floor(n/2)+(-1)^n2^floor(n/2))/2; a(n)=A102560*2^floor(n/2).

CROSSREFS

Sequence in context: A230423 A213672 A004025 * A072068 A078145 A074078

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 November 23 01:23 EST 2014. Contains 249836 sequences.