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%I #7 Feb 17 2019 08:50:52
%S 3,13,305175781
%N Prime repunits in ascending prime bases (written in decimal).
%C 2^2-1=3 is prime; (3^3-1)/2=13 is prime; (5^13-1)/4=305175781 is prime; the next term is too gigantic to be computed simply.
%F a(p)=((p^a(p-1))-1)/(p-1); a(p)=111...111 in base p with a(p-1) 1's; p runs through the primes.
%K nonn,bref,more
%O 1,1
%A Xavier Labouze (Xavier.Labouze(AT)cep.u-psud.fr)
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