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 A179077 #19 Nov 04 2024 01:39:45
%S A179077 1,2,1,4,10,6,9,6,11,2,12,2,5,7,41,19,16,11,20,4,39,38,13,12,17,83,15,
%T A179077 26,25,53,36,34,106,60,43,112,7,134,94,6,100,115,100,15,153,71,7,155,
%U A179077 175,136,14,52,43,243,193,256,251,218,140,148,116,156,281,39,240,33,278
%N A179077 a(n) is the residue ((2^p - 2)/p) mod p, where p is the n-th prime.
%C A179077 a(n) = 0 where n=183 (p=1093) and n=490 (p=3511).
%C A179077 From _Felix Fröhlich_, Sep 13 2019: (Start)
%C A179077 Conjecture: a(n) is the residue A036968(p-1) (mod p) for p = prime(n).
%C A179077 If the above conjecture is true, then a(n) = 0 if and only if p is a Wieferich prime (A001220) (cf. Hu et al., 2019, section 1.3). (End)
%H A179077 Robert Israel, <a href="/A179077/b179077.txt">Table of n, a(n) for n = 1..10000</a>
%H A179077 Su Hu, Min-Soo Kim, Pieter Moree and Min Sha, <a href="https://arxiv.org/abs/1809.08431">Irregular primes with respect to Genocchi numbers and Artin's primitive root conjecture</a>, arXiv:1809.08431 [math.NT], 2019; Journal of Number Theory 205 (2019), 59-80, DOI:<a href="https://doi.org/10.1016/j.jnt.2019.03.012">10.1016/j.jnt.2019.03.012</a>.
%p A179077 f:= p -> (2&^p-2 mod p^2)/p:
%p A179077 seq(f(ithprime(i)),i=1..100);# _Robert Israel_, Nov 03 2024
%t A179077 aa = {}; Do[AppendTo[aa, Mod[(2^Prime[n] - 2)/Prime[n], Prime[n]]], {n, 1, 100}]; aa
%o A179077 (PARI) a(n) = my(p=prime(n)); lift(Mod(((2^p-2)/p), p)) \\ _Felix Fröhlich_, Sep 13 2019
%Y A179077 Cf. A001220, A036968, A377655.
%K A179077 nonn
%O A179077 1,2
%A A179077 _Artur Jasinski_, Jun 28 2010