A242787 Numbers n such that (n^n-2)/(n-2) is an integer.

1, 3, 4, 5, 16, 17, 37, 121, 257, 436, 457, 1297, 2116, 2557, 2705, 3817, 3857, 4357, 5545, 6481, 7876, 8009, 9217, 10441, 10621, 11953, 16213, 20896, 22897, 23437, 26321, 26797, 27841, 28681, 35209, 43057, 44101, 47521, 47881, 49204, 49681, 51121, 57241, 61921, 62569

Offset

1,2

Comments

If m is a nonnegative integer then 2^(2^m)+1 is in the sequence. This implies the sequence is infinite. - Jahangeer Kholdi, Dec 06 2014

Links

Table of n, a(n) for n=1..45.

Example

(5^5-2)/(5-2) = 3123/3 = 1041 is an integer. Thus 5 is a member of this sequence.

Prog

(PARI) for(n=1, 10^6, if(n!=2, s=(n^n-2)/(n-2); if(floor(s)==s, print(n))))

Crossrefs

Sequence in context: A347391 A051033 A346601 * A031199 A173027 A290014

Adjacent sequences: A242784 A242785 A242786 * A242788 A242789 A242790

Keyword

nonn

Author

Derek Orr, May 22 2014

Status

approved