a(1)=2. For n >=2, a(n) = the least integer >= a(n-1) that is not coprime to both a(n-1)+1 and a(n-1).
2, 6, 14, 18, 38, 42, 86, 90, 98, 102, 206, 210, 422, 426, 434, 438, 878, 882, 1766
2 seqfan posts
Mon Feb 9 14:31:01 CET 2009 [seqfan] Re: A sequence closely related to A140525