A138232 - OEIS

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A138232

First differences of A138231.

1, 0, 0, 1, -2, 2, -4, 2, -4, 0, 0, -4, 8, -8, 16, -8, 16, 0, 0, 16, -32, 32, -64, 32, -64, 0, 0, -64, 128, -128, 256, -128, 256, 0, 0, 256, -512, 512, -1024, 512, -1024, 0, 0, -1024, 2048, -2048, 4096, -2048, 4096, 0, 0, 4096, -8192, 8192, -16384, 8192, -16384, 0, 0, -16384, 32768

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OFFSET

0,5

COMMENTS

The sequence contains 2 copies of 1 and 3 copies of the higher powers 2^j (up to sign).

LINKS

Table of n, a(n) for n=0..60.

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

FORMULA

a(n) = 2a(n-2)-2a(n-4). a(n) = -4a(n-8).

a(2n) = (-1)^(n+1)*A090132(n). a(2n+1) = A009545(n).

O.g.f.: (x-1)(x^2-x-1)/(1-2x^2+2x^4). - R. J. Mathar, Jul 08 2008