A043705 Numbers whose base-16 representation has an even number of runs.

16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 86, 87, 88

Offset

1,1

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Mathematica

A043705Q[k_] := EvenQ[Length[Split[IntegerDigits[k, 16]]]];
Select[Range[100], A043705Q] (* Paolo Xausa, Oct 27 2025 *)

Prog

(Python)
from itertools import groupby
def ok(n): return len(list(g for k, g in groupby(hex(n)[2:])))%2 == 0
print(list(filter(ok, range(1, 80)))) # Michael S. Branicky, Jun 18 2021

Crossrefs

Sequence in context: A358677 A085096 A043675 * A178980 A031315 A077914

Adjacent sequences: A043702 A043703 A043704 * A043706 A043707 A043708

Keyword

nonn,base

Author

Clark Kimberling

Extensions

More terms from Paolo Xausa, Oct 27 2025

Status

approved