1,1

Table of n, a(n) for n=1..20.

2*(2^2-1)*(2^3-1)*(2^5-1) + 1 = 1303 prime so k(3)=2

Sequence in context: A213170 A321741 A101416 * A270557 A129365 A125838

Adjacent sequences: A098917 A098918 A098919 * A098921 A098922 A098923

hard,more,nonn

Pierre CAMI, Oct 17 2004

a(15)-a(20) from Donovan Johnson, Mar 23 2008

approved