A029564 - OEIS

%I #14 May 21 2013 11:13:53

%S 1886,50711,149171,222101,628421,766931,1105646,1778621,2523902,

%T 5430047,5836181,6265805,9306986,10671881,12450371,21817715,24953666,

%U 32029934,34836791,38697746,48807671,55252571,57264161,63697721,69300086,74157926

%N Quasi-Carmichael numbers to base -4: squarefree composites n such that prime p|n ==> p+4|n+4.

%H Giovanni Resta, <a href="/A029564/b029564.txt">Table of n, a(n) for n = 1..541</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[#, 4] &] (* _Giovanni Resta_, May 21 2013 *)

%K nonn

%O 1,1

%A _David W. Wilson_