# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a116213 Showing 1-1 of 1 %I A116213 #3 Mar 31 2012 13:20:26 %S A116213 1,3,3855, %T A116213 450552876409790643671482431940419874915447411150352389258589821042463539455 %N A116213 (2^(2^(2^n))-1)/(2^(2^n)+1). %C A116213 2^n+1 divides 2^(2^n)-1 iff n is a power of 2. %F A116213 a(n) = (2^(2^(2^n))-1)/(2^(2^n)+1). a(n) = A051179(2^n)/A000215(n). %t A116213 Table[ (2^2^2^n - 1) / (2^2^n + 1), {n,0,3} ] %Y A116213 Cf. A000215 = Fermat numbers: 2^(2^n)+1. Cf. A051179 = 2^(2^n)-1. %K A116213 nonn %O A116213 0,2 %A A116213 _Alexander Adamchuk_, Apr 08 2007 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE