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 A346940 #18 Aug 31 2021 06:25:24 %S A346940 2357,2582,3334,4714,5774,6667,8165,8819,9428,10542,10543,10544,10545, %T A346940 14907,14908,14909,18257,18258,18259,21081,21082,21083,23570,23571, %U A346940 25819,25820,27888,27889,29813,29814,31622,33332,33333,33335,33336,33337,33338,33339,33340,33341,33342 %N A346940 Numbers whose square starts with exactly 4 identical digits. %C A346940 If m is a term, 10*m is another term. %C A346940 Differs from A132391 where only at least 4 identical digits are required; indeed, 10541 is the first term of A132391 that is not in this sequence (see Example section), the next one is 33346. %e A346940 2357 is a term because 2357^2 = 5555449 starts with four 5's. %e A346940 10541 is not a term because 10541^2 = 111112681 starts with five 1's. %t A346940 q[n_] := SameQ @@ (d = IntegerDigits[n^2])[[1 ;; 4]] && d[[5]] != d[[1]]; Select[Range[100, 33350], q] (* _Amiram Eldar_, Aug 08 2021 *) %o A346940 (Python) %o A346940 def ok(n): %o A346940 s = str(n*n) %o A346940 return len(s) > 4 and s[0] == s[1] == s[2] == s[3] != s[4] %o A346940 print(list(filter(ok, range(33343)))) # _Michael S. Branicky_, Aug 08 2021 %Y A346940 Cf. A346941, A346942. %Y A346940 Supersequences: A131573, A132391. %Y A346940 Similar with: A346812 (2 digits), A346891 (3 digits). %K A346940 nonn,base %O A346940 1,1 %A A346940 _Bernard Schott_, Aug 08 2021