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A346891
Positive numbers whose square starts with exactly 3 identical digits.
3
149, 298, 334, 472, 667, 745, 882, 1054, 1055, 1056, 1057, 1058, 1490, 1491, 1492, 1493, 1825, 1826, 1827, 2108, 2109, 2356, 2581, 2788, 2789, 2980, 2981, 3161, 3162, 3332, 3333, 3335, 3336, 3337, 3338, 3339, 3340, 3341, 3342, 3343, 3344, 3345, 3346
OFFSET
1,1
COMMENTS
If m is a term 10*m is another term.
2357 is the first term of A131573 that is not in this sequence (see Example section), the next ones are 2582, 3334, ...
EXAMPLE
149 is a term because 149^2 = 22201 starts with three 2's.
2357 is not a term because 2357^2 = 5555449 starts with four 5's.
MATHEMATICA
Select[Range[32, 3350], (d = IntegerDigits[#^2])[[1]] == d[[2]] == d[[3]] != d[[4]] &] (* Amiram Eldar, Aug 06 2021 *)
PROG
(Python)
def ok(n): s = str(n*n); return len(s) > 3 and s[0] == s[1] == s[2] != s[3]
print(list(filter(ok, range(3347)))) # Michael S. Branicky, Aug 06 2021
CROSSREFS
Subsequence of A131573.
Cf. A039685 (similar, with "ends"), A346812 (similar, with 2), A346892.
Sequence in context: A140023 A105843 A131573 * A244661 A146137 A071331
KEYWORD
nonn,base
AUTHOR
Bernard Schott, Aug 06 2021
STATUS
approved