A237877 Numbers n such that n | A067439(n).

1, 2, 9, 11, 17, 48, 57, 427, 533, 1661, 2161, 4441, 5428, 41628, 171441, 411735, 555716, 1278525, 4292829, 5174373, 8758407, 680133057

Offset: 1

Author

Paolo P. Lava, Feb 14 2014

Keywords

• nonn
• more

Comments

a(19) > 3000000. - Giovanni Resta, Feb 17 2014

a(23) > 4 * 10^9. - Hiroaki Yamanouchi, Sep 27 2015

Examples

			48 is coprime to 1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47. When 48 is divided by these numbers the remainders are 0, 3, 6, 4, 9, 14, 10, 2, 23, 19, 17, 13, 11, 7, 5, 1. Their sum is 144 and 144 / 48 = 3.
		

Crossrefs

Cf. A067439.

Programs

Maple

with(numtheory);P:=proc(q) local i,n,t; for n from 1 to q do t:=0;
for i from 2 to n-1 do if gcd(i,n)=1 then t:=t+(n mod i); fi; od;
if type(t/n,integer) then print(n); fi; od; end: P(10^6);

PARI

is(n)=sum(i=1, n-1, if(gcd(n, i)==1, n%i))%n==0 \\ Charles R Greathouse IV, Nov 06 2014

Extensions

a(14) from Michel Marcus, Feb 17 2014

a(15)-a(18) from Giovanni Resta, Feb 17 2014

a(19)-a(22) from Hiroaki Yamanouchi, Sep 27 2015