A279426 -id:A279426 - cp's OEIS frontend

A279425 Numbers k such that k^2 has an odd number of digits and the middle digit is 5.

16, 112, 150, 163, 166, 169, 172, 186, 211, 218, 227, 242, 244, 246, 248, 250, 252, 254, 256, 258, 273, 282, 289, 314, 1032, 1037, 1042, 1056, 1061, 1075, 1084, 1089, 1098, 1107, 1116, 1125, 1134, 1138, 1147, 1160, 1173, 1177, 1194, 1198, 1219, 1223, 1227

Offset: 1

Lars Blomberg, Dec 22 2016

			16^2 = 2(5)6, 218^2 = 47(5)24, 1075^2 = 115(5)625.

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

Cf. A279420-A279424, A279426-A279429.

Select[Range[1227], OddQ[len=Length[IntegerDigits[#^2]]]&&Part[IntegerDigits[#^2], (len+1)/2]==5 &] (* Stefano Spezia, Oct 03 2023 *)

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

Original entry on oeis.org

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

Lars Blomberg, Dec 22 2016

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

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

Cf. A279420-A279426, A279428-A279429.

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

cp's OEIS Frontend

A279425 Numbers k such that k^2 has an odd number of digits and the middle digit is 5.

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