A093894 Composite members of A093893.

49, 87, 91, 121, 133, 169, 183, 213, 217, 247, 249, 259, 287, 301, 339, 343, 361, 403, 411, 427, 445, 469, 473, 481, 501, 511, 527, 529, 553, 559, 581, 589, 591, 633, 679, 699, 703, 713, 717, 721, 763, 789, 793, 817, 841, 843, 871, 889, 895, 949, 951, 961

Offset: 1

Author

Amarnath Murthy, Apr 23 2004

Keywords

• nonn

Comments

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

Examples

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

Links

• Charles R. Greathouse IV, Sep 10, 2008, Table of n, a(n) for n = 1..10001

Crossrefs

Cf. A093890, A093891, A093892, A093893.

Programs

Mathematica

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 *)

Extensions

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