OFFSET
1,3
COMMENTS
a(n) = least positive integer k such that tan(n*k) and tan(n*k + k) have opposite signs.
EXAMPLE
The signs of tan(6), tan(12), ..., tan(36) are indicated by - - - - - +; that's five -'s followed by +, so that a(6) = 5.
MATHEMATICA
Table[First[Map[Length, Split[Table[Sign[Tan[k n]], {k, 1, 500}]]]], {n, 1, 100}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Apr 21 2020
STATUS
approved