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.
%I A351897 #9 Feb 26 2022 10:11:00 %S A351897 0,1,2,5,7,11,14,19,23,26,38,55,59,67,71,74,86,103,107,115,119,127, %T A351897 131,139,143,175,179,187,191,223,227,235,239,266,278,314,326,367,371, %U A351897 379,383,415,419,427,431,463,467,475,479,506,518,554,566,607,611,619,623 %N A351897 Numbers that in factorial-base representation have digits with an alternating parity. %H A351897 Amiram Eldar, <a href="/A351897/b351897.txt">Table of n, a(n) for n = 1..20477</a> (terms below 10!) %e A351897 7 is a term since its factorial-base representation is 101 and the parities of its digits are odd, even, odd. %t A351897 max = 7; q[n_] := AllTrue[Differences@ Mod[IntegerDigits[n, MixedRadix[Range[max, 2, -1]]], 2], # != 0 &]; Select[Range[0, 1000], q] %Y A351897 Cf. A007623. %Y A351897 Similar sequences: A000975 (binary), A030141 (decimal), A033068 (ternary), A179970 (quaternary). %Y A351897 Subsequences: A033312, A138524, A341900. %K A351897 nonn,base %O A351897 1,3 %A A351897 _Amiram Eldar_, Feb 24 2022