cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A351897 Numbers that in factorial-base representation have digits with an alternating parity.

Original entry on oeis.org

0, 1, 2, 5, 7, 11, 14, 19, 23, 26, 38, 55, 59, 67, 71, 74, 86, 103, 107, 115, 119, 127, 131, 139, 143, 175, 179, 187, 191, 223, 227, 235, 239, 266, 278, 314, 326, 367, 371, 379, 383, 415, 419, 427, 431, 463, 467, 475, 479, 506, 518, 554, 566, 607, 611, 619, 623
Offset: 1

Views

Author

Amiram Eldar, Feb 24 2022

Keywords

Examples

			7 is a term since its factorial-base representation is 101 and the parities of its digits are odd, even, odd.
		

Crossrefs

Cf. A007623.
Similar sequences: A000975 (binary), A030141 (decimal), A033068 (ternary), A179970 (quaternary).
Subsequences: A033312, A138524, A341900.

Programs

  • Mathematica
    max = 7; q[n_] := AllTrue[Differences@ Mod[IntegerDigits[n, MixedRadix[Range[max, 2, -1]]], 2], # != 0 &]; Select[Range[0, 1000], q]