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%I #4 Dec 20 2022 13:37:57
%S 77767777,77777177,77777377,77777747,137777777,172777777,177677777,
%T 177776777,177777377,177777577,177777727,177777773,177777779,
%U 177797777,197777777,272777777,277177777,277727777,277771777,277775777,277777177
%N Primes with exactly seven 7's.
%t Select[Prime[Range[45*10^5,152*10^5]],DigitCount[#,10,7]==7&] (* _Harvey P. Dale_, Dec 20 2022 *)
%Y Cf. A038618, A178550-5, A178557-8
%K nonn,base
%O 1,1
%A _Lekraj Beedassy_, May 29 2010