A030156 Odd squares in which parity of digits alternates.

1, 9, 25, 49, 81, 121, 169, 361, 529, 729, 961, 4761, 6561, 12321, 12769, 14161, 16129, 18769, 32761, 34969, 56169, 72361, 74529, 76729, 78961, 96721, 212521, 214369, 290521, 436921, 452929, 458329, 474721, 670761, 690561, 1038361

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A030151, A030152, A030155, A030157, A030158.

Programs

Mathematica

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

Extensions

Offset changed by Giovanni Resta, Aug 16 2018