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 A130062 #15 Sep 21 2024 03:50:08
%S A130062 1,21,49,105,1729,2465,2877,7305,10585,15841,31021,31621,32041,41041,
%T A130062 46657,52633,54145,75361,83333,115921,126217,162401,172081,211141,
%U A130062 282133,284649,294409,334153,383161,399001,417241,449065,488881,530881
%N A130062 Nonprime numbers k such that k divides 3^((k+1)/2) - 2^((k+1)/2) - 1.
%C A130062 The perfect squares in listed terms are a(1) = 1, a(3) = 49 = 7^2, a(13) = 32041 = 179^2 and a(29) = 383161 = 619^2.
%C A130062 Note that primes {7,179,619} are the terms of A130060 or primes in A127074.
%H A130062 Amiram Eldar, <a href="/A130062/b130062.txt">Table of n, a(n) for n = 1..1000</a>
%t A130062 Select[ 2*Range[100000]-1, !PrimeQ[ # ] && Mod[ PowerMod[3,(#+1)/2,# ] - PowerMod[2,(#+1)/2,# ] - 1, # ] == 0 & ]
%Y A130062 Cf. A097934 (primes p that divide 3^((p-1)/2) - 2^((p-1)/2)).
%Y A130062 Cf. A038876 (primes p such that 6 is a square mod p).
%Y A130062 Cf. A127071, A127072, A127073, A127074.
%Y A130062 Cf. A130058, A130059, A130061, A130063, A130060, A127074.
%K A130062 nonn
%O A130062 1,2
%A A130062 _Alexander Adamchuk_, May 05 2007
%E A130062 More terms from _Ryan Propper_, Jan 07 2008