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 A346891 #16 May 06 2022 13:13:51 %S A346891 149,298,334,472,667,745,882,1054,1055,1056,1057,1058,1490,1491,1492, %T A346891 1493,1825,1826,1827,2108,2109,2356,2581,2788,2789,2980,2981,3161, %U A346891 3162,3332,3333,3335,3336,3337,3338,3339,3340,3341,3342,3343,3344,3345,3346 %N A346891 Positive numbers whose square starts with exactly 3 identical digits. %C A346891 If m is a term 10*m is another term. %C A346891 2357 is the first term of A131573 that is not in this sequence (see Example section), the next ones are 2582, 3334, ... %e A346891 149 is a term because 149^2 = 22201 starts with three 2's. %e A346891 2357 is not a term because 2357^2 = 5555449 starts with four 5's. %t A346891 Select[Range[32, 3350], (d = IntegerDigits[#^2])[[1]] == d[[2]] == d[[3]] != d[[4]] &] (* _Amiram Eldar_, Aug 06 2021 *) %o A346891 (Python) %o A346891 def ok(n): s = str(n*n); return len(s) > 3 and s[0] == s[1] == s[2] != s[3] %o A346891 print(list(filter(ok, range(3347)))) # _Michael S. Branicky_, Aug 06 2021 %Y A346891 Subsequence of A131573. %Y A346891 Cf. A039685 (similar, with "ends"), A346812 (similar, with 2), A346892. %K A346891 nonn,base %O A346891 1,1 %A A346891 _Bernard Schott_, Aug 06 2021