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 A254502 #33 Mar 21 2019 13:31:56
%S A254502 0,6,31,48,22,599,1102,5280,4667,1753,48861,150336,223254,644487,
%T A254502 7016773,9588848
%N A254502 a(n) is the smallest nonnegative integer such that a(n)! contains a string of exactly n consecutive 7's.
%e A254502 a(1) = 6 since 6! equals 720, which contains '7'.
%t A254502 A254452[n_] := Module[{m = 0},
%t A254502 If[n == 0, While[MemberQ[IntegerDigits[m!], 7], m++]; m,
%t A254502 t = Table[7, n];
%t A254502 While[! MemberQ[Split[IntegerDigits[m!]], t], m++]; m]];
%t A254502 Table[A254452[n], {n, 0, 14}] (* _Robert Price_, Mar 21 2019 *)
%Y A254502 Cf. A254042, A254447, A254448, A254449, A254500, A254501, A254716, A254717.
%K A254502 nonn,base,more
%O A254502 0,2
%A A254502 _Martin Y. Champel_, Jan 31 2015
%E A254502 a(11), a(12) from _Jon E. Schoenfield_, Feb 21 2015
%E A254502 a(0) prepended by _Jon E. Schoenfield_, Mar 01 2015
%E A254502 a(13) from _Jon E. Schoenfield_, Mar 06 2015
%E A254502 a(14)-a(15) from _Bert Dobbelaere_, Oct 29 2018