|
|
A069234
|
|
Numbers k such that the sum over the prime divisors of k equals the number of divisors of k.
|
|
1
|
|
|
2, 9, 84, 126, 135, 196, 264, 294, 375, 468, 567, 594, 625, 1040, 1100, 1232, 1368, 1824, 2028, 2052, 2420, 2704, 2720, 3042, 3400, 4416, 6050, 6125, 7203, 7986, 8019, 8500, 8512, 8575, 8664, 8928, 9200, 9234, 11560, 13020, 16065, 16250, 19305
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
For distinct primes p,q, includes p^a*q^b if (a+1)*(b+1)=p+q. - Robert Israel, Jan 05 2018
|
|
LINKS
|
|
|
FORMULA
|
|
|
MAPLE
|
filter:= n -> numtheory:-tau(n)=convert(numtheory:-factorset(n), `+`):
|
|
MATHEMATICA
|
Select[Range[20000], Plus @@ ((f = FactorInteger[#])[[;; , 1]]) == Times @@ (f[[;; , 2]] + 1) &] (* Amiram Eldar, Jun 06 2022 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
easy,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|