2249999

Appears in sequences

• Lucas-Carmichael numbers of the form k^2 - 1.at n=7A292538
• a(1) = 2, a(n) = k - 1, where k is the least number greater than a(n-1) such that rad(k) | a(n-1), where rad(n) = A007947(n).at n=26A365413