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 A199984 #12 Apr 28 2018 16:20:10 %S A199984 4,14,22,27,39,72,93,98,114,122,141,172,189,198,212,217,221,249,266, %T A199984 294,319,333,338,346,364,391,411,429,436,492,626,634,662,712,721,767, %U A199984 772,776,793,819,833,891,913,918,924,931,942,973,981,1114,1122,1127,1139 %N A199984 Composite numbers whose multiplicative digital root is 4. %C A199984 Complement of A199983 with respect to A034051. %e A199984 Number 172 is in sequence because 1*7*2=14, 1*4=4. %t A199984 cn4Q[n_]:=NestWhile[Times@@IntegerDigits[#]&,n,#>9&]==4; Select[Select[ Range[ 1200],CompositeQ],cn4Q] (* _Harvey P. Dale_, Apr 28 2018 *) %Y A199984 Cf. A199983 (primes whose multiplicative digital root is 4). %Y A199984 Cf. A034051 (numbers whose multiplicative digital root is 4). %K A199984 nonn,base %O A199984 1,1 %A A199984 _Jaroslav Krizek_, Nov 13 2011