9765620domain: NAppears in sequencesNumber of primitive (aperiodic) palindromes using a maximum of five different symbols.at n=18A056461Number of primitive (period n) periodic palindromes using a maximum of five different symbols.at n=18A056496a(n) = 5^n - 5.at n=10A178671a(n) = n^10 - n.at n=5A196291