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 A093894 Composite members of A093893. 2

%I #11 Sep 23 2018 21:42:07

%S 49,87,91,121,133,169,183,213,217,247,249,259,287,301,339,343,361,403,

%T 411,427,445,469,473,481,501,511,527,529,553,559,581,589,591,633,679,

%U 699,703,713,717,721,763,789,793,817,841,843,871,889,895,949,951,961

%N Composite members of A093893.

%C Comment: Most terms of this sequence have four divisors. Some terms (the squares of primes) have three divisors; very few terms have more than four divisors (the first such term is 4753, with six). Conjecture: This sequence is infinite. - Adam M. Kalman (mocha(AT)clarityconnect.com), Nov 11 2004

%H Charles R. Greathouse IV, Sep 10, 2008, <a href="/A093894/b093894.txt">Table of n, a(n) for n = 1..10001</a>

%e 133 is a term, the divisors are 1,7,19,133 and no sum of two or more gives a prime.

%t For[a:=4, a<=2000, s =Divisors[a];n := 1;d := False; While[(n<=2^Length[s])\[And]( ["not" character]d), If[Length[NthSubset[n, s]]>=2, If[ !PrimeQ[Plus@@NthSubset[n, s]], n++, d:= True], n++ ]]; If[ ["not" character]d, Print[a]];a++;While[PrimeQ[a], a+=2]]; (* Adam M. Kalman, Nov 11 2004 *)

%Y Cf. A093890, A093891, A093892, A093893.

%K nonn

%O 1,1

%A _Amarnath Murthy_, Apr 23 2004

%E Corrected and extended by Adam M. Kalman (mocha(AT)clarityconnect.com), Nov 11 2004

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Last modified June 22 23:47 EDT 2024. Contains 373629 sequences. (Running on oeis4.)