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 A276733 #17 Sep 30 2016 13:27:09 %S A276733 341,1247,1387,2047,2701,3277,3683,4033,4369,4681,5461,5963,7957,8321, %T A276733 9017,9211,10261,13747,14351,14491,15709,17593,18721,19951,20191, %U A276733 23377,24929,25351,29041,31417,31609,31621,33227,35333,37901,42799,45761,46513,49141,49601,49981 %N A276733 Composite numbers n such that 2^lpf(n) == 2 (mod n), where lpf(n) = A020639(n). %C A276733 Super-Poulet numbers A050217 is a subsequence. %C A276733 From _Robert Israel_, Sep 16 2016: (Start) %C A276733 If p is a Wieferich prime (A001220), p^2 is in this sequence. %C A276733 If p is a non-Wieferich prime, there are terms of the sequence divisible by p iff p < A006530(2^p-2). Is the latter true for all primes p except 2,3,5,7 and 13? (End) %H A276733 Robert Israel, <a href="/A276733/b276733.txt">Table of n, a(n) for n = 1..1000</a> %p A276733 filter:= n -> not isprime(n) and 2 &^ min(numtheory:-factorset(n)) - 2 mod n = 0: %p A276733 select(filter, [seq(i,i=3..100000,2)]); # _Robert Israel_, Sep 16 2016 %o A276733 (PARI) lista(nn) = forcomposite(n=2, nn, if (Mod(2, n)^factor(n)[1,1] == Mod(2, n), print1(n, ", "));); \\ _Michel Marcus_, Sep 16 2016 %Y A276733 Cf. A006530, A020639, A050217. %K A276733 nonn %O A276733 1,1 %A A276733 _Thomas Ordowski_, Sep 16 2016 %E A276733 More terms from _Michel Marcus_, Sep 16 2016