A351895 Numbers with an equal number of odd and even digits in their factorial-base representation.

2, 5, 25, 26, 29, 30, 34, 37, 38, 41, 42, 46, 51, 55, 56, 59, 63, 67, 68, 71, 73, 74, 77, 78, 82, 85, 86, 89, 90, 94, 99, 103, 104, 107, 111, 115, 116, 119, 723, 727, 728, 731, 735, 739, 740, 743, 745, 746, 749, 750, 754, 757, 758, 761, 762, 766, 771, 775, 776

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Wikipedia, Factorial number system.

Index entries for sequences related to factorial base representation.

Example

5 is a term since its factorial-base representation, 21, has one odd digit, 1, and one even digit, 2.

Mathematica

max = 7; fctBaseDigits[n_] := IntegerDigits[n, MixedRadix[Range[max, 2, -1]]]; Select[Range[1, max!], EvenQ[Length[(d = fctBaseDigits[#])]] && Count[d, _?EvenQ] == Length[d]/2 &]

Crossrefs

Cf. A007623, A351893, A351894.

A138524 is a subsequence.

Similar sequences: A031443 (binary), A227870 (decimal).

Sequence in context: A120759 A326971 A000895 * A109306 A009560 A333591

Adjacent sequences: A351892 A351893 A351894 * A351896 A351897 A351898

Keyword

nonn,base

Author

Amiram Eldar, Feb 24 2022

Status

approved