786458domain: NAppears in sequencesa(n) is the smallest number such that twice the number of divisors of (a(n)-n)/3 gives the n-th term in the first differences of the sequence produced by the Flavius Josephus sieve, A000960.at n=25A130826a(n) = 48*2^n + 26 (n>=1).at n=13A304605