A288657 Numbers whose squares have an odd number of digits.

0, 1, 2, 3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131

Offset

1,3

Comments

The sequence of squares starts: 0, 1, 4, 9, 100, 121, 144, 169, 196, 225, 256, ...

Links

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

Jeremy Gardiner, Middle digit in square numbers, Seqfan Mailing list, Dec 12 2016.

Mathematica

Join[{0}, Select[Range[150], OddQ[IntegerLength[#^2]]&]] (* Harvey P. Dale, Apr 07 2018 *)

Crossrefs

Cf. A288658, A288659, A288660.

Sequence in context: A225558 A362089 A301382 * A055655 A371030 A276326

Adjacent sequences: A288654 A288655 A288656 * A288658 A288659 A288660

Keyword

nonn,base,easy

Author

Lars Blomberg, Jun 13 2017

Status

approved