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 A064522 For an integer n with prime factorization p1*p2*p3* ... *pn let n* = (p1-1)*(p2-1)*(p3-1)* ... *(pn-1) (A003958); sequence gives n such that n is divisible by n*. 3

%I

%S 1,2,4,6,8,12,16,20,24,32,36,40,48,64,72,80,84,96,120,128,144,160,168,

%T 192,216,240,256,272,288,312,320,336,384,400,432,440,480,504,512,544,

%U 576,624,640,672,720,768,800,864,880,960,1008,1024,1088,1152,1248,1280

%N For an integer n with prime factorization p1*p2*p3* ... *pn let n* = (p1-1)*(p2-1)*(p3-1)* ... *(pn-1) (A003958); sequence gives n such that n is divisible by n*.

%H Harry J. Smith, <a href="/A064522/b064522.txt">Table of n, a(n) for n = 1..1000</a>

%p with(numtheory); ListA064522:=proc(q) local a,b,i,n;

%p for n from 1 to q do a:=ifactors(n)[2]; b:=mul((a[i][1]-1)^a[i][2],i=1..nops(a)); if type(n/b,integer) then print(n); fi; od; end: ListA064522(10^6); # _Paolo P. Lava_, Jul 02 2013

%o (PARI) nsm(n)= { local(f,p=1); f=factor(n); for(i=1, matsize(f)[1], p*=(f[i, 1] - 1)^f[i, 2]); return(p) } { n=0; for (m=1, 10^9, if (m%nsm(m) == 0, write("b064522.txt", n++, " ", m); if (n==1000, break)) ) } \\ _Harry J. Smith_, Sep 17 2009

%Y Cf. A064476, A003958.

%K nonn

%O 1,2

%A _Vladeta Jovovic_, Oct 07 2001

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Last modified September 17 06:00 EDT 2019. Contains 327119 sequences. (Running on oeis4.)