[sweety439]

Originally Posted by JeppeSN

OK, it is a reference to Krywaruczenko, Daniel (2008) "A Reverse Sierpinski Number Problem," Rose-Hulman Undergraduate Mathematics Journal: Vol. 9 : Iss. 2 , Article 4. I will fix the link to that paper in OEIS. /JeppeSN

For A263500, I found a(n) for all n<=64 in the post http://mersenneforum.org/showpost.ph...56&postcount=2.