A023886 Average of proper divisors (excluding 1) is an integer.

4, 8, 9, 15, 18, 21, 25, 27, 33, 35, 39, 45, 49, 51, 55, 57, 63, 65, 69, 75, 77, 81, 85, 87, 91, 93, 95, 98, 99, 111, 115, 117, 119, 121, 123, 125, 128, 129, 133, 141, 143, 145, 147, 153, 155, 159, 161, 162, 169, 171, 175, 177, 183, 185, 187, 201, 203

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Mathematica

Select[Range[210], IntegerQ[Mean[Rest[Most[Divisors[#]]]]]&]  (* Harvey P. Dale, Feb 20 2011 *)

Crossrefs

Sequence in context: A373375 A336663 A329936 * A158337 A161542 A131195

Adjacent sequences: A023883 A023884 A023885 * A023887 A023888 A023889

Keyword

nonn

Author

Olivier Gérard

Extensions

Clarified definition -- Harvey P. Dale, Feb 20 2011

Status

approved