A235331 Numbers with odious squares.

1, 2, 4, 5, 7, 8, 9, 10, 11, 14, 16, 17, 18, 19, 20, 22, 23, 25, 28, 29, 31, 32, 33, 34, 35, 36, 38, 39, 40, 41, 43, 44, 46, 49, 50, 51, 55, 56, 58, 59, 62, 64, 65, 66, 67, 68, 70, 71, 72, 75, 76, 77, 78, 79, 80, 82, 85, 86, 87, 88, 89, 91, 92, 95, 97, 98, 100

Offset: 1

Author

Gerasimov Sergey, Jan 06 2014

Keywords

• nonn
• easy

Comments

Numbers that are sqrt(odious squares).

Examples

			1 = sqrt(A235001(1)) = sqrt(1).
2 = sqrt(A235001(2)) = sqrt(4).
4 = sqrt(A235001(3)) = sqrt(16).
5 = sqrt(A235001(4)) = sqrt(25).
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..2600

Crossrefs

Cf. A235001, A194991.

Programs

Magma

[n : n in [0..130] |IsOdd(&+Intseq(n^2, 2))]; // Vincenzo Librandi, Jan 31 2018

Mathematica

Select[Range[200], OddQ[DigitCount[#^2, 2][[1]]] &] (* Vincenzo Librandi, Jan 31 2018 *)

PARI

isok(n) = (hammingweight(n^2) % 2) == 1; \\ Michel Marcus, Jan 31 2018

Formula

a(n) = sqrt(A235001(n)).