Voozh

A030155

Odd n such that in n^2 the parity of digits alternates.

1, 3, 5, 7, 9, 11, 13, 19, 23, 27, 31, 69, 81, 111, 113, 119, 127, 137, 181, 187, 237, 269, 273, 277, 281, 311, 461, 463, 539, 661, 673, 677, 689, 819, 831, 1019, 1027, 1111, 1113, 1119, 1127, 1137, 1269, 1277, 1287, 1361, 1369, 1377, 1863, 1969

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

OFFSET

1,2

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..10000

MATHEMATICA

altQ[n_] := n < 10 || Union[Total /@ Partition[ Mod[ IntegerDigits@n, 2], 2, 1]] == {1}; Select[ Range[1, 2000, 2], altQ[#^2] &] (* Giovanni Resta, Aug 16 2018 *)

CROSSREFS

Cf. A030151, A030152, A030156, A030157, A030158.

Sequence in context: A133854 A239008 A291343 * A143448 A226484 A261213

Adjacent sequences: A030152 A030153 A030154 * A030156 A030157 A030158

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

EXTENSIONS

Offset changed by Giovanni Resta, Aug 16 2018

STATUS

approved

URL: https://oeis.org/A030155

⇱ A030155 - OEIS