A279421 Numbers k such that k^2 has an odd number of digits and the middle digit is 1.

1, 110, 119, 123, 127, 131, 142, 152, 182, 190, 210, 224, 237, 239, 261, 263, 276, 290, 310, 1035, 1040, 1059, 1073, 1087, 1096, 1105, 1123, 1132, 1141, 1145, 1154, 1167, 1171, 1184, 1188, 1209, 1213, 1217, 1285, 1289, 1293, 1312, 1316, 1331, 1346, 1357, 1368

Offset

1,2

Links

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

Example

1^2 = (1), 190^2 = 36(1)00, 1145^2 = 131(1)025.

Mathematica

ond1Q[n_]:=Module[{len=IntegerLength[n^2]}, OddQ[len]&&IntegerDigits[n^2][[(len+1)/2]]==1]; Select[Range[1500], ond1Q] (* Harvey P. Dale, Jun 06 2018 *)

Crossrefs

Cf. A279420, A279422-A279429.

Sequence in context: A267254 A036230 A171236 * A135642 A166323 A194429

Adjacent sequences: A279418 A279419 A279420 * A279422 A279423 A279424

Keyword

nonn,base,easy

Author

Lars Blomberg, Dec 22 2016

Status

approved