638401domain: NAppears in sequencesNumbers n for which the absolute values of the abundances of n, n^2 and n^3 are all prime numbers.at n=3A125249Number of positive integer solutions to the Diophantine equation x + y + 2z = n^2.at n=39A218832a(n) = (1-2*n^2)^2.at n=20A239607