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 A279422 #7 Oct 03 2023 19:06:54 %S A279422 11,15,18,23,25,27,101,106,115,135,149,159,162,165,168,171,174,185, %T A279422 193,198,203,208,215,222,233,235,265,267,278,285,292,297,302,307,315, %U A279422 1001,1006,1011,1016,1021,1026,1031,1045,1050,1064,1069,1078,1083,1092,1101 %N A279422 Numbers k such that k^2 has an odd number of digits and the middle digit is 2. %H A279422 Lars Blomberg, <a href="/A279422/b279422.txt">Table of n, a(n) for n = 1..10000</a> %e A279422 11^2 = 1(2)1, 135^2 = 18(2)25, 285^2 = 81(2)25. %t A279422 Select[Range[1101], OddQ[len=Length[IntegerDigits[#^2]]]&&Part[IntegerDigits[#^2], (len+1)/2]==2 &] (* _Stefano Spezia_, Oct 03 2023 *) %Y A279422 Cf. A279420-A279421, A279423-A279429. %K A279422 nonn,base,easy %O A279422 1,1 %A A279422 _Lars Blomberg_, Dec 22 2016