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 A346812 #16 May 06 2022 13:13:51 %S A346812 15,21,34,47,58,67,88,94,105,106,107,108,109,150,151,182,183,184,210, %T A346812 211,212,235,236,257,258,278,279,297,315,316,332,333,335,336,337,338, %U A346812 339,340,341,342,343,344,345,346,470,471,473,474,475,476,477,478,479,575,576,577,578,579,580,581 %N A346812 Positive numbers whose square starts with exactly 2 identical digits. %C A346812 If m is a term, then 10*m is another term. %e A346812 34 is a term because 34^2 = 1156. %e A346812 149 is not a term because 149^2 = 22201. %t A346812 Select[Range[10, 600], (d = IntegerDigits[#^2])[[1]] == d[[2]] != d[[3]] &] (* _Amiram Eldar_, Aug 05 2021 *) %o A346812 (Python) %o A346812 def ok(n): s = str(n*n); return len(s) > 2 and s[0] == s[1] != s[2] %o A346812 print(list(filter(ok, range(582)))) # _Michael S. Branicky_, Aug 05 2021 %o A346812 (PARI) isok(m) = my(d=digits(m^2)); (#d > 2) && (d[2] == d[1]) && (d[3] != d[2]); \\ _Michel Marcus_, Aug 05 2021 %Y A346812 Subsequence of A123912. %Y A346812 A346774 is a subsequence. %Y A346812 Cf. A186438, A186439, A346678 (similar, with "ends"). %K A346812 nonn,base %O A346812 1,1 %A A346812 _Bernard Schott_, Aug 05 2021