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 A084004 #10 Sep 22 2024 13:52:06
%S A084004 64,7921,9604,164836,351649,996004,19758025,20647936,29757025,
%T A084004 30846916,97990201,99960004,1203187969,1975180249,3086469136,
%U A084004 4265657344,8143618564,9999600004,115644884356,131504868496,132231867769,140039859961,173879826121,339900660100,391600608400
%N A084004 Squares obtained as a concatenation of k and 10's complement of k.
%H A084004 Andrew Howroyd, <a href="/A084004/b084004.txt">Table of n, a(n) for n = 1..65</a>
%F A084004 a(n) = A084005(n)^2. - _Andrew Howroyd_, Sep 21 2024
%o A084004 (PARI) b(n)={my(k=logint(n,10)+1); (n+1)*10^k - n}
%o A084004 { for(k=1, 10^6, my(x=b(k)); if(issquare(x), print1(x, ", "))) } \\ _Andrew Howroyd_, Sep 22 2024
%Y A084004 Cf. A084005, A084006, A084007.
%K A084004 base,nonn
%O A084004 1,1
%A A084004 _Amarnath Murthy_, May 23 2003
%E A084004 More terms from _Ray Chandler_, May 31 2003
%E A084004 Offset changed and a(22) onwards from _Andrew Howroyd_, Sep 21 2024