A279427 Numbers k such that k^2 has an odd number of digits and the middle digit is 7.

24, 26, 113, 137, 144, 154, 181, 189, 214, 223, 234, 266, 277, 286, 311, 1033, 1038, 1043, 1057, 1062, 1071, 1076, 1085, 1099, 1108, 1117, 1126, 1139, 1148, 1152, 1161, 1165, 1178, 1182, 1199, 1203, 1228, 1232, 1236, 1240, 1244, 1248, 1252, 1256, 1260, 1264

Offset: 1

Author

Lars Blomberg, Dec 22 2016

Keywords

• nonn
• base
• easy

Examples

			24^2 = 5(7)6, 223^2 = 49(7)29, 1152^2 = 132(7)104.
		

Links

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

Crossrefs

Cf. A279420-A279426, A279428-A279429.

Programs

Mathematica

Select[Range[1264], OddQ[len=Length[IntegerDigits[#^2]]]&&Part[IntegerDigits[#^2], (len+1)/2]==7 &] (* Stefano Spezia, Oct 03 2023 *)