OFFSET
1
FORMULA
a(n) = [2^n/(1 - cos(1/n))] - [2^n/(-1 + cot(1/n))] - [2^n/(1 - cos(1/n) -2^n/(-1 + cot(1/n))], where [ ] = floor.
MATHEMATICA
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Apr 05 2020
STATUS
approved