OFFSET
0,5
LINKS
Ilya Gutkovskiy, Scatter plot of a(n) up to n=50000
FORMULA
a(n) = Sum_{k=1..n} a(2*k-1) = Sum_{k=1..n} (-1)^(n-k) * a(2*k).
a(2^k) = 2^floor(k/2).
MATHEMATICA
a[0] = 0; a[1] = 1; a[n_] := a[n] = If[EvenQ[n], a[(n - 2)/2] + a[n/2], a[(n + 1)/2] - a[(n - 1)/2]]; Table[a[n], {n, 0, 75}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Sep 04 2019
STATUS
approved