This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A131459 #3 Nov 11 2010 07:34:06 %S A131459 0,4,28,124,601,8188,131068,524284,5758678,269332797,2147483644, %T A131459 60499757946,322343434415,5567835897839,16557488261208, %U A131459 7853427629182494,426047939903614778,2305843009213693948,141920345591572240917 %N A131459 Residues of 3^(2^(p(n)-1)) for Mersenne numbers with prime indices. %C A131459 Mp is prime iff 3^(2^(p(n)-1)) is congruent to (-3) Mod Mp. Thus M7 = 127 is prime because 3^64 Mod 127 = 124 (=127-3) while M11 = 2047 is composite because 3^1024 Mod 2047 <> 2044. %H A131459 Dennis Martin, <a href="/A131459/b131459.txt">Table of n, a(n) for n = 1..100</a> %F A131459 a(n) = 3^(2^(p(n)-1)) Mod 2^p(n)-1 %e A131459 a(5) = 3^(2^(11-1)) Mod 2^11-1 = 3^1024 Mod 2047 = 601 %Y A131459 Cf. A095847, A001348, A131458, A131460, A131461, A131462, A131463. %K A131459 nonn %O A131459 1,2 %A A131459 Dennis Martin (dennis.martin(AT)dptechnology.com), Jul 13 2007, Jul 20 2007