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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
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
k such that A000005(k) = A008472(k).
MAPLE
filter:= n -> numtheory:-tau(n)=convert(numtheory:-factorset(n), `+`):
select(filter, [$1..10^5]); # Robert Israel, Jan 05 2018
MATHEMATICA
Select[Range[20000], Plus @@ ((f = FactorInteger[#])[[;; , 1]]) == Times @@ (f[[;; , 2]] + 1) &] (* Amiram Eldar, Jun 06 2022 *)
CROSSREFS
Sequence in context: A375838 A354045 A296581 * A086929 A193466 A354310
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, Apr 13 2002
STATUS
approved