A049306 Numbers k such that k is a substring of 8^k.

4, 6, 7, 10, 13, 17, 18, 28, 31, 33, 36, 38, 42, 44, 47, 48, 49, 52, 54, 56, 58, 60, 63, 64, 67, 68, 69, 76, 77, 79, 81, 82, 83, 85, 86, 89, 90, 91, 94, 97, 112, 115, 124, 130, 135, 165, 173, 176, 178, 189, 193, 195, 206, 208, 215, 221, 225, 249, 251, 252, 253, 256

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base
• easy

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001018, A032740, A049301, A049302, A049303, A049304, A049305, A049307.

Programs

Mathematica

Select[Range[300],SequenceCount[IntegerDigits[8^#],IntegerDigits[#]]>0&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Dec 16 2018 *)

Python

def ok(n): return str(n) in str(8**n)
print(list(filter(ok, range(257)))) # Michael S. Branicky, Aug 13 2021