A032913 Numbers whose set of base-6 digits is {1,3}.

1, 3, 7, 9, 19, 21, 43, 45, 55, 57, 115, 117, 127, 129, 259, 261, 271, 273, 331, 333, 343, 345, 691, 693, 703, 705, 763, 765, 775, 777, 1555, 1557, 1567, 1569, 1627, 1629, 1639, 1641, 1987, 1989, 1999, 2001, 2059, 2061, 2071, 2073

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A007092, A032917.

Programs

Magma

[n: n in [1..2500] | Set(IntegerToSequence(n, 6)) subset {1, 3}]; // Vincenzo Librandi, Jun 01 2012

Mathematica

Flatten[Table[FromDigits[#,6]&/@Tuples[{1,3},n],{n,5}]] (* Harvey P. Dale, Nov 16 2011 *)

Python

def A032913(n): return (int(bin(m:=n+1)[3:],6)<<1) + (6**(m.bit_length()-1)-1)//5 # Chai Wah Wu, Oct 13 2023