[seqfan] Re: Chain of semiprimes: a(n)=least semiprime p*q such that a(n-1)=p+q.

Hans Havermann pxp at rogers.com
Fri Sep 17 03:27:08 CEST 2010

> a(n) = least semiprime (p*q), iterating a(n+1) = p+q, that generates a
> chain of n semiprimes:

As a proof-of-concept calculation, here is a chain of 100 semiprimes:


I'm not suggesting that the first number is minimal. (In fact, I'd be  
surprised if it was.) You are welcome to find a smaller start. (It's  
not as easy as it might appear.)

More information about the SeqFan mailing list