OFFSET
1
FORMULA
a(n) = [2^n csc(1/n)] - [2^n cot(1/n)] - [2^n (csc(1/n) - cot(1/n))], where [ ] = floor.
MATHEMATICA
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Mar 11 2020
STATUS
approved