4317391domain: NAppears in sequencesSmallest palindromic number of 5 digits in two bases differing by n.at n=21A216899Triangular numbers T(i) that can be expressed as the sum of 2 positive triangular numbers, T(j)+T(k), and for which i+j+k is a triangular number, where T is A000217.at n=30A343426