This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A178556 #4 Dec 20 2022 13:37:57 %S A178556 77767777,77777177,77777377,77777747,137777777,172777777,177677777, %T A178556 177776777,177777377,177777577,177777727,177777773,177777779, %U A178556 177797777,197777777,272777777,277177777,277727777,277771777,277775777,277777177 %N A178556 Primes with exactly seven 7's. %t A178556 Select[Prime[Range[45*10^5,152*10^5]],DigitCount[#,10,7]==7&] (* _Harvey P. Dale_, Dec 20 2022 *) %Y A178556 Cf. A038618, A178550-5, A178557-8 %K A178556 nonn,base %O A178556 1,1 %A A178556 _Lekraj Beedassy_, May 29 2010