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A029559 Quasi-Carmichael numbers to base 4: squarefree composites n such that (n,2*3) = 1 and prime p|n ==> p-4|n-4. 2

%I #15 May 21 2013 11:15:00

%S 1705,7015,31369,53599,77809,215635,244885,248239,346801,568879,

%T 662935,898105,2151769,2240515,2782579,9480829,10665265,11219485,

%U 13644085,13929205,16549579,17782879,21592289,29354329,30075565,35448439,39792379

%N Quasi-Carmichael numbers to base 4: squarefree composites n such that (n,2*3) = 1 and prime p|n ==> p-4|n-4.

%C If multiples of 2 and 3 are not excluded, then terms like 6, 10, 15, 30, 70, 130, 165,... belong to the sequence. - _Giovanni Resta_, May 21 2013

%H Giovanni Resta, <a href="/A029559/b029559.txt">Table of n, a(n) for n = 1..372</a> (terms < 10^12)

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

%t qcm[n_, d_] := Block[{p, e}, {p, e} = Transpose@FactorInteger@n; Length[p] > 1 && Max[e] == 1 && d < Min[p] && And @@ IntegerQ /@ ((n - d)/(p - d))]; Select[Range[10^6], qcm[#, 4] &] (* _Giovanni Resta_, May 21 2013 *)

%K nonn

%O 1,1

%A _David W. Wilson_

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Last modified May 23 05:11 EDT 2024. Contains 372758 sequences. (Running on oeis4.)