A053609 Primes of form x^2+1 where x = LCM(1,2,...,k) for some k.

2, 5, 37, 176401, 129859329601, 516625648014869290354797521879383114125823989794742396526049715541246671360001

Offset: 1

Author

Labos Elemer, Feb 09 2000

Keywords

• nonn
• hard

Comments

The next term has k > 10^4, if it exists. - Amiram Eldar, Aug 23 2024

Crossrefs

Cf. A049536, A046029, A051739, A051418, A051451, A053608.

Programs

Mathematica

Select[FoldList[LCM, 1, Select[Range[100], PrimePowerQ]]^2 + 1, PrimeQ] (* Amiram Eldar, Aug 23 2024 *)

Formula

a(n) = A053608(A053608(n)) = A053608(n)^2 + 1. - Amiram Eldar, Aug 23 2024