OFFSET
1,1
COMMENTS
a(n) = least positive integer k such that sin(n*k) and sin(n*k + k) have opposite signs.
EXAMPLE
The signs of sin(6), sin(12), sin(18), ..., sin(72) are indicated by - - - - - - - - - - - + ; that's eleven -'s followed by +, so that a(6) = 11.
MATHEMATICA
Table[First[Map[Length, Split[Table[Sign[Sin[k n]], {k, 1, 500}]]]], {n, 1, 100}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Apr 21 2020
STATUS
approved