3000000001domain: NAppears in sequencesNumbers k such that k^2+k+7 is a palindrome.at n=26A027722a(n) = sqrt(A077204(n)).at n=18A077205a(1) = 1; for n>1, a(n) = smallest number > a(n-1) such that last digit of a(n-1) + first digit of a(n) = 3.at n=28A098408a(n) = 3*10^n + 1.at n=9A199683