1210121domain: NAppears in sequencesNumbers n such that the set S(n) = {k: k + reverse(k) = n} is not empty, at least one element of S(n) has the same number of digits as n and at least one element of S(n) has one digit less than n has.at n=10A088171Palindromes of the form i^2 + reverse(i)^2.at n=22A256398