A279422 Numbers k such that k^2 has an odd number of digits and the middle digit is 2.

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

Lars Blomberg, Table of n, a(n) for n = 1..10000

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

Cf. A279420-A279421, A279423-A279429.

Sequence in context: A069822 A116999 A309362 * A333488 A053675 A031944

Adjacent sequences: A279419 A279420 A279421 * A279423 A279424 A279425

Keyword

nonn,base,easy

Author

Lars Blomberg, Dec 22 2016

Status

approved