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 A280447 #8 Jan 05 2017 05:49:38 %S A280447 176594,281894,371894,446594,1765940,2818940,2822594,3718940,3722594, %T A280447 4465940,17659400,28189400,28225940,37189400,37225940,44659400 %N A280447 Like A065759 but where f(n) = 3*n. %C A280447 Numbers of the form 176594*10^k, 281894*10^k, 371894*10^k, 446594*10^k, etc., with k>=0, belong to the sequence. %e A280447 176594 = concat(1,76594) = concat(17,6594) = concat(176,594) = concat(1765,94) = concat(17659,4) and (1*76594 + 17*6594 + 176*594 + 1765*94 + 17659*4) = 529782 = 3*176594. %p A280447 P:=proc(q) local a,k,n; for n from 1 to q do a:=0; %p A280447 for k from 1 to ilog10(n) do a:=a+(n mod 10^k)*trunc(n/10^k); od; %p A280447 if a/n=3 then print(n); fi; od; end: P(10^9); %Y A280447 Cf. A065759, A280445, A280446. %K A280447 nonn,base,more %O A280447 1,1 %A A280447 _Paolo P. Lava_, Jan 03 2017