

A104904


Numbers n such that d(n)*pi(n)=n, where d(n) is the number of positive divisors of n.


2




OFFSET

1,1


COMMENTS

Next term is greater than 3*10^9.


LINKS

Table of n, a(n) for n=1..8.


EXAMPLE

189961452 is in the sequence because d(189961452)=18; pi(189961452)=10553414 & 18*10553414=189961452.


MATHEMATICA

Do[If[DivisorSigma[0, n]*PrimePi[n] == n, Print[n]], {n, 2000000000}]


CROSSREFS

Cf. A063903, A104905, A104906.
Sequence in context: A322126 A272241 A171939 * A272247 A167748 A203755
Adjacent sequences: A104901 A104902 A104903 * A104905 A104906 A104907


KEYWORD

hard,more,nonn


AUTHOR

Farideh Firoozbakht, Apr 12 2005


EXTENSIONS

a(5)a(8) from Donovan Johnson, Dec 08 2009


STATUS

approved



