A355275 - OEIS

%I #12 Mar 04 2024 01:31:18

%S 1,4,10,12,13,14,16,22,31,37,39,40,41,43,49,67,85,91,93,94,95,97,103,

%T 109,111,112,113,115,117,118,119,120,121,122,123,124,125,127,129,130,

%U 131,133,139,145,147,148,149,151,157,175,193,199,201,202,203,205,211,229,256,274,280,282,283,284,286,292

%N Numbers having more odd than even digits when written in base 3.

%C If k is a term, then so is 3*k+1. - _Robert Israel_, Mar 04 2024

%H Robert Israel, <a href="/A355275/b355275.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= proc(n) local L;

%p   L:= convert(n,base,3);

%p   numboccur(1,L) > nops(L)/2

%p end proc:

%p select(filter, [$1..1000]); # _Robert Israel_, Mar 04 2024

%o (PARI) select( {is_A355275(n)=vecsum(n=digits(n,3)%2)*2>#n}, [0..299])

%o (Python)

%o from sympy.ntheory import digits

%o def ok(n):

%o     d = digits(n, 3)[1:]

%o     return len(d) < 2*sum(1 for di in d if di%2)

%o print([k for k in range(293) if ok(k)]) # _Michael S. Branicky_, Jul 03 2022

%Y Cf. A072600 (same in base 2), A352547 (same in base 10).

%K nonn,base

%O 1,2

%A _M. F. Hasler_, Jul 03 2022