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A116974 Numbers n for which the sum of the proper divisors equals the product of the proper divisors. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A238463 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

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Last modified December 7 20:23 EST 2019. Contains 329847 sequences. (Running on oeis4.)