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 A073866 #19 Dec 21 2024 15:19:21
%S A073866 4,6,8,9,28,39,68,69,88,99,299,399,589,699,799,899,999,2899,3999,5999,
%T A073866 6999,7999,9899,9999,29999,39999,58999,69999,89999,99999,299899,
%U A073866 399999,499999,689999,699999,889999,999999,1999999,3899999,3999999,5899999,6999999,8999999,9999999
%N A073866 a(n) is the smallest composite number with the sum of digits = the n-th composite number.
%H A073866 Sean A. Irvine, <a href="/A073866/b073866.txt">Table of n, a(n) for n = 1..1000</a>
%e A073866 a(5) = 28, because 10 is the 5th composite, and 28 is the first composite with sum of digits equal to 10. - _Michel Marcus_, May 19 2014
%o A073866 (PARI) lista(nn) = {vn = vector(nn, i, i); vc = select(x->iscomp(x), vn); vsd = vector(#vc, i, sumdigits(vc[i])); for (i=1, #vc, print1(vc[select(x->(x==vc[i]), vsd, 1)[1]], ", "););} \\ _Michel Marcus_, May 19 2014
%Y A073866 Cf. A002808, A073868, A075360.
%K A073866 base,nonn
%O A073866 1,1
%A A073866 _Amarnath Murthy_, Aug 15 2002
%E A073866 More terms from _Michel Marcus_, May 19 2014