A067852 Numbers k that divide prime(k^2) - 1.

1, 2, 4, 6, 10, 11, 18, 20, 32, 90, 129, 188, 244, 678, 688, 756, 1081, 1322, 1477, 19758, 21351, 29518, 43187, 49978, 50342, 95708, 182326, 248253

Offset: 1

Author

Joseph L. Pe, Feb 15 2002

Keywords

• nonn
• more
• hard

Comments

a(29) > 3*10^5. - Donovan Johnson, Nov 15 2009

Any further terms are > 10^6. - Lucas A. Brown, Sep 27 2024

Examples

			6 divides prime(6^2)-1 = 150, so 6 is a term of the sequence.
		

Links

• Lucas A. Brown, Python program.

Crossrefs

Cf. A000040, A011757, A067851.

Programs

Mathematica

Select[Range[10^4], Mod[Prime[ #^2] - 1, # ] == 0 &]

PARI

isok(k) = !((prime(k^2)-1) % k); \\ Michel Marcus, Aug 15 2021

Extensions

a(20)-a(28) from Donovan Johnson, Nov 15 2009