A062061 Numbers k such that prime(k)+1 divides k^2.

2, 4, 70, 516, 174080, 292050, 637320, 687105342, 14342420320, 214517880600

Offset

1,1

Comments

a(9) > 3*10^9. - Donovan Johnson, Oct 14 2009

a(11) > 3*10^11. - Giovanni Resta, Apr 15 2017

Links

Table of n, a(n) for n=1..10.

Example

Prime(4)+1 = 7+1 divides 4^2, so 4 is a term of the sequence.

Mathematica

Select[Range[10^6], Mod[ #^2, Prime[ # ] + 1] == 0 &]
Select[Range[640000], PowerMod[#, 2, Prime[#]+1]==0&] (* The program generates the first seven terms of the sequence. To generate more, increase the Range constant. *) (* Harvey P. Dale, Apr 23 2022 *)

Prog

(PARI) isok(n) = n^2 % (prime(n)+1) == 0; \\ Michel Marcus, Apr 15 2017

Crossrefs

Cf. A045924, A061437.

Sequence in context: A362456 A301818 A054920 * A066974 A270583 A018373

Adjacent sequences: A062058 A062059 A062060 * A062062 A062063 A062064

Keyword

nonn

Author

Joseph L. Pe, Feb 13 2002

Extensions

a(8) from Donovan Johnson, Oct 14 2009

a(9)-a(10) from Giovanni Resta, Apr 15 2017

Status

approved