A053608 Numbers x = LCM(1,2,...,k) such that x^2 + 1 is prime.

1, 2, 6, 420, 360360, 718766754945489455304472257065075294400

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. A003418, A049536, A046029, A051418, A051451, A051739, A053609.

Programs

Mathematica

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