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 A061386 #12 Sep 08 2022 08:45:03 %S A061386 3,15,24,33,42,51,60,108,117,126,135,144,153,162,171,180,207,216,225, %T A061386 234,243,252,261,270,306,315,324,333,342,351,360,405,414,423,432,441, %U A061386 450,504,513,522,531,540,603,612,621,630,702,711,720,801,810,900,1029 %N A061386 Sum of digits = 3 times number of digits. %e A061386 126 is a term as the arithmetic mean of the digits is (1+2+6)/3 = 3. %t A061386 Select[Range[1200],3IntegerLength[#]==Total[IntegerDigits[#]]&] (* _Harvey P. Dale_, Feb 04 2011 *) %o A061386 (Magma) [ n: n in [1..1030] | &+Intseq(n) eq 3*#Intseq(n) ]; // _Bruno Berselli_, Jun 30 2011 %Y A061386 Cf. A061383-A061388, A061423-A061425. %K A061386 nonn,base,easy %O A061386 1,1 %A A061386 _Amarnath Murthy_, May 03 2001 %E A061386 More terms from Larry Reeves (larryr(AT)acm.org), May 16 2001