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A279422
Numbers k such that k^2 has an odd number of digits and the middle digit is 2.
3
11, 15, 18, 23, 25, 27, 101, 106, 115, 135, 149, 159, 162, 165, 168, 171, 174, 185, 193, 198, 203, 208, 215, 222, 233, 235, 265, 267, 278, 285, 292, 297, 302, 307, 315, 1001, 1006, 1011, 1016, 1021, 1026, 1031, 1045, 1050, 1064, 1069, 1078, 1083, 1092, 1101
OFFSET
1,1
LINKS
EXAMPLE
11^2 = 1(2)1, 135^2 = 18(2)25, 285^2 = 81(2)25.
MATHEMATICA
Select[Range[1101], OddQ[len=Length[IntegerDigits[#^2]]]&&Part[IntegerDigits[#^2], (len+1)/2]==2 &] (* Stefano Spezia, Oct 03 2023 *)
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Lars Blomberg, Dec 22 2016
STATUS
approved