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A070990
First differences of A002487.
3
1, -1, 2, -1, 1, -2, 3, -1, 2, -3, 3, -2, 1, -3, 4, -1, 3, -4, 5, -3, 2, -5, 5, -2, 3, -5, 4, -3, 1, -4, 5, -1, 4, -5, 7, -4, 3, -7, 8, -3, 5, -8, 7, -5, 2, -7, 7, -2, 5, -7, 8, -5, 3, -8, 7, -3, 4, -7, 5, -4, 1, -5, 6, -1, 5, -6, 9, -5, 4, -9, 11, -4, 7, -11, 10, -7, 3, -10, 11, -3, 8, -11, 13, -8, 5, -13, 12, -5, 7, -12, 9, -7, 2, -9, 9, -2, 7, -9, 12, -7
OFFSET
0,3
FORMULA
-a(2n+3) = a(2n) = A002487(n+2), n >= 0. - Ralf Stephan, Aug 17 2003
G.f.: -1/x^2 + ((1 - x)/x^2)*Product_{k>=0} (1 + x^(2^k) + x^(2^(k+1))). - Ilya Gutkovskiy, Feb 28 2017
CROSSREFS
Cf. A002487.
Sequence in context: A118492 A079246 A309014 * A097868 A025830 A083796
KEYWORD
sign
AUTHOR
N. J. A. Sloane, May 24 2002
STATUS
approved