A346891 Positive numbers whose square starts with exactly 3 identical digits.

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

Author

Bernard Schott, Aug 06 2021

Keywords

• nonn
• base

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, ...

Examples

			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.
		

Crossrefs

Subsequence of A131573.

Cf. A039685 (similar, with "ends"), A346812 (similar, with 2), A346892.

Programs

Mathematica

Select[Range[32, 3350], (d = IntegerDigits[#^2])[[1]] == d[[2]] == d[[3]] != d[[4]] &] (* Amiram Eldar, Aug 06 2021 *)

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