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A029567 Quasi-Carmichael numbers to base -7: squarefree composites n such that prime p|n ==> p+7|n+7. 2

%I

%S 273,2093,2387,2585,6545,7553,11433,11753,16653,19865,33473,34265,

%T 35105,37433,53345,72065,88193,99209,120089,124733,136793,149753,

%U 155873,158723,159581,164423,198653,203573,232193,257033,263993,284303,349265,372053

%N Quasi-Carmichael numbers to base -7: squarefree composites n such that prime p|n ==> p+7|n+7.

%H Giovanni Resta, <a href="/A029567/b029567.txt">Table of n, a(n) for n = 1..7312</a> (terms < 10^12)

%H <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>

%t qcp[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n;

%t Length[p] > 1 && Max[e] == 1 && And @@ IntegerQ /@ ((n + d)/(p + d))]; Select[Range[10^6], qcp[#, 7] &] (* _Giovanni Resta_, May 21 2013 *)

%K nonn

%O 1,1

%A _David W. Wilson_

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Last modified April 19 21:57 EDT 2021. Contains 343117 sequences. (Running on oeis4.)