A116974 Numbers n for which the sum of the proper divisors equals the product of the proper divisors.

2, 3, 5, 6, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277

Offset

1,1

Links

Table of n, a(n) for n=1..60.

Formula

Union of 6 and A000040: the prime numbers.

Mathematica

fQ[n_] := Block[{id = Most@Divisors@n}, Plus @@ id == Times @@ id]; Select[Range@300, fQ@# &] (* Robert G. Wilson v, Apr 03 2006 *)

Prog

(PARI) a(n)=if(n<5, [2, 3, 5, 6][n], prime(n+1)) \\ Charles R Greathouse IV, Aug 26 2011

Crossrefs

Sequence in context: A340150 A166070 A053813 * A031402 A019438 A023798

Adjacent sequences: A116971 A116972 A116973 * A116975 A116976 A116977

Keyword

nonn,easy

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 01 2006

Status

approved