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

1, 2, 6, 420, 360360, 718766754945489455304472257065075294400

Offset

1,2

Comments

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

Links

Table of n, a(n) for n=1..6.

Mathematica

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

Crossrefs

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

Sequence in context: A092024 A252741 A069261 * A199239 A123261 A124061

Adjacent sequences: A053605 A053606 A053607 * A053609 A053610 A053611

Keyword

nonn,hard

Author

Labos Elemer, Feb 09 2000

Status

approved