A288657 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

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.