A049305 Numbers k such that k is a substring of 7^k.

3, 4, 6, 8, 12, 15, 20, 40, 42, 43, 50, 53, 55, 59, 60, 61, 62, 69, 72, 73, 74, 75, 78, 79, 80, 81, 83, 86, 87, 88, 89, 93, 94, 95, 96, 97, 99, 100, 103, 111, 113, 114, 118, 164, 165, 185, 193, 200, 207, 210, 215, 220, 230, 232, 238, 241, 243, 250, 253, 254, 255

Offset

1,1

Links

Table of n, a(n) for n=1..61.

Prog

(Python)
def ok(n): return str(n) in str(7**n)
print(list(filter(ok, range(256)))) # Michael S. Branicky, Aug 13 2021

Crossrefs

Cf. A000420, A032740, A049301-A049307.

Sequence in context: A225531 A129295 A192276 * A147606 A279083 A298805

Adjacent sequences: A049302 A049303 A049304 * A049306 A049307 A049308

Keyword

nonn,base,easy

Author

David W. Wilson

Status

approved