32212156416domain: NAppears in sequencesSum of all proper base 4 numbers with n digits (those not beginning with 0).at n=8A121544a(n) = 6*a(n-1) - 8*a(n-2), for n > 2, with a(0) = 1, a(1) = 6, a(2) = 27.at n=17A171475