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 A051809 #8 Jan 18 2019 14:11:09 %S A051809 7,17,70,71,107,117,170,171,257,275,527,572,700,701,710,711,725,752, %T A051809 1007,1017,1070,1071,1107,1117,1170,1171,1257,1275,1527,1572,1700, %U A051809 1701,1710,1711,1725,1752,2057,2075,2157,2175 %N A051809 Numbers with nonzero multiplicative digital root 7. %H A051809 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>. %F A051809 A051802^-1(7) %t A051809 Select[Range[2500],NestWhile[Times@@(IntegerDigits[#]/.(0->1))&,#,#>9&] == 7&] (* _Harvey P. Dale_, Jan 18 2019 *) %Y A051809 Part of histogram of A051802. %K A051809 nonn,easy,base %O A051809 1,1 %A A051809 _Dan Hoey_, Dec 09 1999