53943domain: NAppears in sequencesa(n+1) = Sum_{k=0..floor(2*n/5)} a(k) * a(n-k).at n=19A030037G.f. satisfies: A(x) = Sum_{n>=0} x^n*A(x)^binomial(n+2,3).at n=8A191809a(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).at n=9A299640