A393803 - OEIS

%I #47 Apr 13 2026 22:37:12

%S 0,1,2,5,10,12,13,14,20,22,24,25,26,33,35,36,37,38,42,43,53,69,71,72,

%T 73,74,77,88,100,106,113,116,120,121,122,124,137,138,139,142,147,150,

%U 151,154,156,157,158,178,184,197,201,203,204,205,206,209,210,211,214,226,228,229

%N Numbers whose number of nonzero digits is identical in base 2 and 3.

%H Vincenzo Manto, <a href="/A393803/b393803.txt">Table of n, a(n) for n = 1..9999</a>

%p q:= n-> (f-> f(n, 2)=f(n, 3))((k, b)-> nops(subs(0=[][], convert(k, base, b)))):

%p select(q, [$0..230])[];  # _Alois P. Heinz_, Apr 01 2026

%t q[k_] := DigitCount[k, 2, 1] == Total[DigitCount[k, 3, {1, 2}]]; Select[Range[0, 230], q] (* _Amiram Eldar_, Mar 29 2026 *)

%o (Python)

%o def nonzero_digits(n, b):

%o     count = 0

%o     while n > 0:

%o         if n % b: count += 1

%o         n //= b

%o     return count

%o def ok(n):

%o     return nonzero_digits(n, 2) == nonzero_digits(n, 3)

%o print([k for k in range(230) if ok(k)]) # _Vincenzo Manto_, Apr 08 2026

%Y Cf. A000120, A160384.

%K nonn,base

%O 1,3

%A _Vincenzo Manto_, Mar 29 2026