Composites Of This Sequence

[David Wilson]

Leroy Quet wrote:
> By the way,
> All terms of A037074 are included in the sequence of the composites of A143578.
>
> Are there any other composites?
>
> Thanks,
> Leroy Quet
>   

Empirically, all of the elements of A143578 seem to have <= 2 prime 
divisors.

If true, then A143578 has the following characterization:

A143578 = {1} U primes U {pq: p, q prime, p+q | p^2-1}

The latter set includes the products of twin primes A037074, as well as 
other composites, e.g, 5*19.