|
|
A111113
|
|
a(2^m) = 1, a(2^m+1) = -1 (m>0), otherwise a(n) = 0.
|
|
1
|
|
|
0, 0, 1, -1, 1, -1, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
LINKS
|
|
|
FORMULA
|
G.f.: (1 - x) * (Sum_{k>0} x^(2^k)). - Michael Somos, Aug 03 2009
|
|
EXAMPLE
|
G.f. = x^2 - x^3 + x^4 - x^5 + x^8 - x^9 + x^16 - x^17 + x^32 - x^33 + ...
|
|
PROG
|
(PARI) {a(n) = if( n<2, 0, [1, -1, 0] [1 + min(2, n - 2^(length(binary(n)) - 1))] )} /* Michael Somos, Aug 03 2009 */
(PARI) {a(n) = if( n<2, 0, if( n%2, -a(n - 1), n == 2^valuation(n, 2)))} /* Michael Somos, Aug 03 2009 */
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|