A089751 a(n) = the first prime in the orbit of n under f(n) = n^2 + 1, if it exists; = 0 otherwise.

2, 2, 3, 17, 5, 37, 7, 17859077

Offset

1,1

Comments

Question: Is a(n) > 0 for all n?

a(9) may be equal to 0. - Michel Marcus, May 19 2013

Links

Table of n, a(n) for n=1..8.

Example

4 -> 4^2 + 1 = 17 (prime). So a(4) = 17.

Prog

(PARI) a(n) = {while(! isprime(n), n = n^2 + 1; ); return (n); } \\ Michel Marcus, May 19 2013

Crossrefs

Cf. A002522.

Sequence in context: A341768 A184840 A164022 * A137909 A035796 A049009

Adjacent sequences: A089748 A089749 A089750 * A089752 A089753 A089754

Keyword

nonn,more

Author

Joseph L. Pe, Jan 08 2004

Status

approved