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%I #20 Jul 08 2023 21:07:21
%S 17,1433,499679,1279,31,149
%N Smallest prime factor of Googolplex - n which exceeds 16.
%C Seventh term is not known. Sequence continues ?, 625392489737, 19, 37, 5419, 107, 23, 60149, 1733, 89, 8543, 17, 5261, 229, 8656871, 4273, 14009, 29, 509, 43628661784403, 24539783, 19, 347, 12414692011, 523, 151, 421, 35816135619181, 17, 23, 184309, ?, 181, 288481, 163, 41, 743, 13337, 71, 53, 19, 59, 113, 37957721, ... where the unknown numbers exceed 25 * 10^12. - _Dario Alpern_, Jul 03 2003
%H Dario Alejandro Alpern, <a href="https://www.alpertron.com.ar/GOOGOLM.HTM">Factors of 1000 numbers up to googolplex</a>.
%t (* For any individual n *) k = 17; While[ !PrimeQ[k] || PowerMod[10, 10^100, k] - n != 0, k += 2]; k
%o (PARI) a(n) = forprime(p=17, oo, if(Mod(10, p)^lift(Mod(10, p-1)^100) == n, return(p))); \\ _Jinyuan Wang_, Apr 17 2020
%Y Cf. A072288.
%K nonn,hard,more,fini
%O 1,1
%A _Ed Pegg Jr_ and _Robert G. Wilson v_, Dec 06 2002
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