|
%I #27 Jul 07 2015 22:20:58
%S 1,2,3,6,10,15,21,30,42,70,110,210,255,285,465,510,570,930,1430,2530,
%T 2590,2870,3010,4970,6699,13398,27645,28785,54435,55290,57570,64790,
%U 65535,66990,69105,78285,108870,118910,131070,138210,156570,224510
%N Squarefree nonprimes n with a divisor d such that phi(n) divides n+d.
%C There are only 42 such numbers below 3*10^5. - _M. F. Hasler_, Apr 06 2013
%H Donovan Johnson, <a href="/A217741/b217741.txt">Table of n, a(n) for n = 1..200</a>
%e For n=70, phi(70)=24 and 2 is a divisor of 70; since 24 | 70+2, the number n=70 is a term of this sequence.
%o (PARI) is(n)=issquarefree(n)&&sumdiv(n,d,(n+d)%eulerphi(n)==0) \\ _Charles R Greathouse IV_, Apr 02 2013
%o (PARI) is_A217741(n)={ my(p); issquarefree(n) && fordiv(n+!p=eulerphi(n), d, (n+d)%p || return(1))} \\ - _M. F. Hasler_, Apr 06 2013
%K nonn
%O 1,2
%A _J. M. Bergot_, Apr 02 2013
%E Name corrected by _Donovan Johnson_, Apr 08 2013
|
