a(0) = 0, and for n > 0, (a(n)) gives the indices n for which d(n) < d(k) for k < n, where d is the difference sequence of (cos k + sin k).

A299640

a(0) = 0, and for n > 0, (a(n)) gives the indices n for which d(n) < d(k) for k < n, where d is the difference sequence of (cos k + sin k).