a(n) = -1 + 2 * product_{i=0..n} A093179(i), where A093179(i) is the smallest prime factor of 2^(2^i) + 1.

A259534

a(n) = -1 + 2 * product_{i=0..n} A093179(i), where A093179(i) is the smallest prime factor of 2^(2^i) + 1.

Terms

    a(0) =5a(1) =29a(2) =509a(3) =131069a(4) =8589934589

External references