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 A344828 #10 Oct 10 2023 12:14:43 %S A344828 557,1207,1451,13543,24675,39016,217682,165407,1357748,399254,1146590, %T A344828 325346,1895206,3365181,4674177,21251205,40698745,6795147,36463448, %U A344828 12717474,54383927,7411274,35989426,101112784,86045167,13128506,276293632,169093089,223680564,137073637 %N A344828 a(n) is the smallest b > 1 such that prime(n), prime(n+1), prime(n+2) and prime(n+3) are all base-b Wieferich primes. %H A344828 Max Alekseyev, <a href="/A344828/b344828.txt">Table of n, a(n) for n = 1..100</a> %o A344828 (PARI) a(n) = my(v=[prime(n)]); while(#v < 4, v=concat(v, nextprime(v[#v]+1))); for(b=2, oo, for(k=1, #v, if(Mod(b, v[k]^2)^(v[k]-1)!=1, break, if(k==#v, return(b))))) %Y A344828 Cf. A039678, A259075. Column 4 of A286816. %Y A344828 Cf. smallest b > 1 such that prime(n+i) is a base-b Wieferich prime for each i = 0..k: A039678 (k=0), A259075 (k=1), A344827 (k=2), A344829 (k=4), A344830 (k=5), A344831 (k=6), A344832 (k=7). %K A344828 nonn %O A344828 1,1 %A A344828 _Felix Fröhlich_, May 29 2021 %E A344828 Terms a(24) onward from _Max Alekseyev_, Oct 10 2023