33268domain: NAppears in sequencesa(n) = a(n-1) + R(a(n-2)) + R(a(n-3)) + R(a(n-4)) where a(1) = a(2) = a(3) = a(4) = 1 and R(n) (A004086) is the reverse of n.at n=15A074865Number of compositions of n such that the cardinality of the set of parts is 2.at n=21A131661Numbers k such that 2*10^k + 93 is prime.at n=27A275523