68864domain: NAppears in sequencesNumbers n such that every digit of n and n-th prime contains a loop (only digits 0,4,6,8,9 in n and n-th prime).at n=22A107624Integers x such that there exist four integers 0<y<=z<=t<=w such that psi(x)^4 = x^4 + y^4 + z^4 + t^4 + w^4.at n=2A391536