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 A346812 Positive numbers whose square starts with exactly 2 identical digits. 3
 15, 21, 34, 47, 58, 67, 88, 94, 105, 106, 107, 108, 109, 150, 151, 182, 183, 184, 210, 211, 212, 235, 236, 257, 258, 278, 279, 297, 315, 316, 332, 333, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 470, 471, 473, 474, 475, 476, 477, 478, 479, 575, 576, 577, 578, 579, 580, 581 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If m is a term, then 10*m is another term. LINKS Table of n, a(n) for n=1..60. EXAMPLE 34 is a term because 34^2 = 1156. 149 is not a term because 149^2 = 22201. MATHEMATICA Select[Range[10, 600], (d = IntegerDigits[#^2])[[1]] == d[[2]] != d[[3]] &] (* Amiram Eldar, Aug 05 2021 *) PROG (Python) def ok(n): s = str(n*n); return len(s) > 2 and s[0] == s[1] != s[2] print(list(filter(ok, range(582)))) # Michael S. Branicky, Aug 05 2021 (PARI) isok(m) = my(d=digits(m^2)); (#d > 2) && (d[2] == d[1]) && (d[3] != d[2]); \\ Michel Marcus, Aug 05 2021 CROSSREFS Subsequence of A123912. A346774 is a subsequence. Cf. A186438, A186439, A346678 (similar, with "ends"). Sequence in context: A190358 A090999 A123912 * A296244 A309005 A225916 Adjacent sequences: A346809 A346810 A346811 * A346813 A346814 A346815 KEYWORD nonn,base AUTHOR Bernard Schott, Aug 05 2021 STATUS approved

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Last modified June 4 21:13 EDT 2023. Contains 363130 sequences. (Running on oeis4.)