[seqfan] Re: Sets of composite numbers

Don Reble djr at nk.ca
Tue Jul 29 07:42:00 CEST 2014


> First, note that these are different: A075067 claims to be looking for
> at least n consecutive, while A189118 is looking for exactly n.

    Other way 'round, actually.

    I say A075067 is correct. It is a trivial variation of A000230 and
    A045881; perhaps it should refer to them.

> In A075067, a(4) through a(6) should all be 115. There are probably
> further errors.

    In A189118, that is. The stated definition gives A100964(n+1)+2.
    But the A189118 terms are
        a(n) = smallest composite (odd) number greater than a(n-1),
        such that a(n)+2n is the first prime after a(n).
    I guess that's what the Mathematica program produces. (Can someone
    confirm that?)

-- 
Don Reble  djr at nk.ca




More information about the SeqFan mailing list