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 A144777 #9 May 17 2024 15:29:28
%S A144777 18,27,36,45,54,63,72,81,90,1089,1098,1179,1188,1197,1269,1278,1287,
%T A144777 1296,1359,1368,1377,1386,1395,1449,1458,1467,1476,1485,1494,1539,
%U A144777 1548,1557,1566,1575,1584,1593,1629,1638,1647,1656,1665,1674,1683,1692,1719
%N A144777 Integers having decimal digital mean equal to zero.
%C A144777 Define the digital mean of n in base b, dm(b, n), to be (Sum_{i=1..d} 2*d_i - (b-1)) / (2*d), where d is the number of digits in the base b representation of n and d_i the individual digits.
%C A144777 a(n) is the subset of multiples of nine for which dm(10, n) = 0; that is, two times the sum of the digits is equal to nine times the number of digits.
%H A144777 Paolo Xausa, <a href="/A144777/b144777.txt">Table of n, a(n) for n = 1..10000</a>
%t A144777 Select[Range[200]*9, 2*DigitSum[#] == 9*IntegerLength[#] &] (* _Paolo Xausa_, May 17 2024 *)
%Y A144777 Cf. A007953, A008591.
%K A144777 base,easy,nonn
%O A144777 1,1
%A A144777 _Reikku Kulon_, Sep 21 2008