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 A217142 Least number m such that phi(m) = phi(m+6n) and m is not divisible by n. 1

%I

%S 143,52,101,124,104,123,183,156,248,144,208,267,241,365,219,248,312,

%T 306,496,369,288,432,241,543,369,468,482,386,730,444,438,432,496,1220,

%U 624,779,612,801,915,744,723,582,576,1095,864,488,482,641,1086,674,738

%N Least number m such that phi(m) = phi(m+6n) and m is not divisible by n.

%H Donovan Johnson, <a href="/A217142/b217142.txt">Table of n, a(n) for n = 2..1000</a>

%o (PARI) fpr(Nmax, lim) = {for (i=2, Nmax,N = i*6;op = vector(N);f = 0;for (n=1, lim, if (op[n%N+1]+0==op[n%N+1]=eulerphi(n), if ((n-N) % i != 0, f = n-N;break;);););print1(f, ", "););}

%Y Cf. A000010, A179188, A217068, A217139, A217141.

%K nonn

%O 2,1

%A _Michel Marcus_, Sep 27 2012

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Last modified December 6 16:24 EST 2019. Contains 329808 sequences. (Running on oeis4.)