52050domain: NAppears in sequencesa(n) = n * Sum_{d|n} d*2^(d-1).at n=9A074225Row sums of A075652.at n=29A075650Numbers k such that 1*k + 1, 3*k + 1, 9*k + 1, 27*k + 1 are all primes.at n=37A112041Numbers k such that k and k^2 use only the digits 0, 2, 5, 7 and 9.at n=47A136917