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 A061104 #16 Dec 06 2024 21:43:35
%S A061104 0,1,4,9,79,799,9999,499999,19999999,999999999,199999999999,
%T A061104 49999999999999,9999999999999999,7999999999999999999,
%U A061104 7999999999999999999999,9999999999999999999999999
%N A061104 Smallest number whose sum of digits is n^2.
%H A061104 Harry J. Smith, <a href="/A061104/b061104.txt">Table of n, a(n) for n = 0..94</a>
%F A061104 a(n) = A051885(n^2).
%F A061104 a(n) = ((n^2 mod 9) + 1)*10^floor(n^2/9) - 1. - _Henry Bottomley_, Apr 24 2001
%e A061104 a(5) = 799, 7 + 9 + 9 = 25 = 5^2.
%o A061104 (PARI) a(n) = { (n^2%9 + 1)*10^(n^2\9) - 1 } \\ _Harry J. Smith_, Jul 18 2009
%Y A061104 Cf. A051885, A061105.
%K A061104 nonn,base
%O A061104 0,3
%A A061104 _Amarnath Murthy_, Apr 20 2001