5242878domain: NAppears in sequencesa(n) = 5*2^n - 2.at n=20A051633Number of palindromes (in base 4) below 4^n.at n=20A117863Start with 1, then alternately add 2 or double.at n=41A123208a(n) = 5*2^(n-2) - 2 for n > 1, with a(1) = 1.at n=21A131051Row sums of triangle A134061.at n=20A134062