A037440 Positive numbers having the same set of digits in base 7 and base 10.

1, 2, 3, 4, 5, 6, 23, 46, 265, 316, 1030, 1234, 1336, 1366, 1401, 1431, 1443, 1454, 1464, 2060, 2116, 3261, 3515, 3621, 4631, 5052, 10144, 10342, 10542, 11134, 11425, 11524, 11544, 12415, 12450, 12532, 12564, 12651, 13035, 13045, 13245

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Examples

			1336 is in the sequence because 1336 in base 7 is 3616.
		

Links

• John Cerkan, Table of n, a(n) for n = 1..10000

Crossrefs

Subsequence of A037404.

Cf. A007093.

Programs

Mathematica

Select[Range@ 13300, Union@ IntegerDigits@ # == Union@ IntegerDigits[#, 7] &] (* Michael De Vlieger, Feb 18 2017 *)

PARI

isok(n) = Set(digits(n, 7)) == Set(digits(n)); \\ Michel Marcus, Feb 18 2017

Python

from sympy.ntheory import digits
def ok(n): return set(map(int, str(n))) == set(digits(n, 7)[1:])
print([k for k in range(1, 10**6) if ok(k)]) # Michael S. Branicky, Apr 22 2023

Extensions

More terms from Don Reble, Apr 28 2006

Edited by John Cerkan, Feb 17 2017