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%I #24 Oct 03 2018 18:41:05
%S 1428571,1428571428571428571428571
%N Primes formed by the initial digits of the decimal expansion of 1/7, starting at the first nonzero digit in the expansion.
%C Next term has 355 digits.
%C All terms are of the form 6x+1; a(4) has 823 digits; and there are no further terms up to and including 10000 digits. - _Harvey P. Dale_, Oct 03 2018
%t Select[Table[FromDigits[PadRight[{},6n+1,{1,4,2,8,5,7}]],{n,200}],PrimeQ](* _Harvey P. Dale_, Oct 03 2018 *)
%Y Cf. A020806, A241217.
%Y Corresponding sequences for 1/k: A093676 (k=12), A242826 (k=13), A242827 (k=14), A242828 (k=17), A242833 (k=19).
%K nonn,base,bref
%O 1,1
%A _Felix Fröhlich_, May 23 2014
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