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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. 0
 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 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: A170866 A125636 A156323 * A276831 A180024 A178197 Adjacent sequences:  A286813 A286814 A286815 * A286817 A286818 A286819 KEYWORD nonn,tabl,more AUTHOR Felix FrÃ¶hlich, May 27 2017 STATUS approved

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Last modified February 24 08:17 EST 2020. Contains 332201 sequences. (Running on oeis4.)