55955domain: NAppears in sequencesa(n) = smallest palindrome > a(n-1) such that a(1)*a(2)*...*a(n) - 1 is a prime.at n=40A051954Palindromic Smith numbers.at n=30A098834Numbers k with digits 5 and 9 only.at n=34A284382a(n) = 5*(10^(2*n+1)-1)/9 + 4*10^n.at n=2A332159Numbers k such that k - A224787(k) is a square.at n=26A386623