OFFSET
0,1
FORMULA
For n > 0, a(n) = n^n*(h(n)^(-n) + h(n)^n) where h(n) = (1 + i*sqrt(4*n^2 - 1))/(2*n).
For n > 0, a(n) = 2 * n^n * cos(n*arctan(sqrt(4*n^2 - 1))). - Vladimir Reshetnikov, Oct 14 2018
CROSSREFS
KEYWORD
sign
AUTHOR
Peter Luschny, Oct 14 2018
STATUS
approved