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 A286816 Smallest b such that the k consecutive primes starting with prime(n) are all base-b Wieferich primes, i.e., satisfy b^(p-1) == 1 (mod p^2). Square array A(n, k), read by antidiagonals downwards. 6
 5, 17, 8, 449, 26, 7, 557, 226, 18, 18, 19601, 1207, 1207, 148, 3, 132857, 54568, 1451, 606, 239, 19 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Array starts 5, 17, 449, 557, 19601, 132857 8, 26, 226, 1207, 54568, 2006776 7, 18, 1207, 1451, 13543, 296449 18, 148, 606, 13543, 296449, 17134811 3, 239, 3469, 24675, 3414284, 36763941 19, 249, 653, 39016, 14380864, 34998229 LINKS Table of n, a(n) for n=1..21. EXAMPLE The sequence of base-226 Wieferich primes starts 3, 5, 7, 97, 157, ... Since 226 is the smallest b such that the three consecutive primes starting with prime(2) = 3 are base-b Wieferich primes, A(2, 3) = 226. PROG (PARI) primevec(initialp, vecsize) = my(v=[initialp]); while(#v < vecsize, v=concat(v, nextprime(v[#v]+1))); v a(n, k) = my(v=primevec(prime(n), k), b=2, i=0); while(1, for(x=1, #v, if(Mod(b, v[x]^2)^(v[x]-1)!=1, i++; break)); if(i==0, return(b)); b++; i=0) array(rows, cols) = for(s=1, rows, for(t=1, cols, print1(a(s, t), ", ")); print("")) array(5, 6) \\ print 5 X 6 array CROSSREFS Cf. A256236, A258787. Sequence in context: A125636 A355658 A156323 * A276831 A180024 A356403 Adjacent sequences: A286813 A286814 A286815 * A286817 A286818 A286819 KEYWORD nonn,tabl,more AUTHOR Felix Fröhlich, May 27 2017 STATUS approved

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Last modified September 28 14:46 EDT 2023. Contains 365736 sequences. (Running on oeis4.)