7891163domain: NAppears in sequencesa(n) = a(1) + a(2) + ... + a(n-1) - a(m), where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = 1 and a(3) = 2.at n=25A049889