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 A131460 #3 Nov 11 2010 07:34:06 %S A131460 0,5,22,118,1803,8182,131062,524278,498820,271127480,2147483638, %T A131460 44060320367,967030303245,7907414671310,49672464783624, %U A131460 5545884378065500,125222315103997360,2305843009213693942,130613131595363896897 %N A131460 Residues of 3^(2^(p(n)-1)+1) for Mersenne numbers with prime indices. %C A131460 Mp is prime iff 3^(2^(p(n)-1)+1) is congruent to (-9) Mod Mp. Thus M7 = 127 is prime because 3^65 Mod 127 = 118 (=127-9) while M11 = 2047 is composite because 3^1025 Mod 2047 <> 2038. %H A131460 Dennis Martin, <a href="/A131460/b131460.txt">Table of n, a(n) for n = 1..100</a> %F A131460 a(n) = 3^(2^(p(n)-1)+1) Mod 2^p(n)-1 %e A131460 a(5) = 3^(2^(11-1)+1) Mod 2^11-1 = 3^1025 Mod 2047 = 1803 %Y A131460 Cf. A095847, A001348, A131458, A131459, A131461, A131462, A131463. %K A131460 nonn %O A131460 1,2 %A A131460 Dennis Martin (dennis.martin(AT)dptechnology.com), Jul 13 2007, Jul 20 2007