110060domain: NAppears in sequencesNumbers n such that there are (presumably) nine palindromes in the Reverse and Add! trajectory of n.at n=16A090070Race of lucky numbers of the form 4*k - 1 vs. 4*k + 1 is tied at the a(n)-th lucky number.at n=19A330359a(n) = Sum_{k=1..n} k * sigma_2(k).at n=23A356125