A049303 Numbers k such that k is a substring of 5^k.

2, 5, 6, 7, 9, 19, 25, 32, 34, 36, 41, 54, 55, 56, 59, 62, 64, 67, 69, 70, 71, 75, 80, 81, 82, 84, 86, 87, 89, 92, 93, 95, 96, 111, 115, 125, 128, 140, 163, 166, 177, 178, 189, 192, 205, 212, 219, 221, 226, 233, 236, 242, 258, 259, 267, 294, 303, 309, 323, 327, 329

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base
• easy

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000351, A032740, A049301, A049302, A049304, A049305, A049306, A049307.

Programs

Mathematica

ss5nQ[n_]:=Module[{len=IntegerLength[n]},MemberQ[Partition[ IntegerDigits[ 5^n], len,1],IntegerDigits[n]]]; Select[Range[400],ss5nQ] (* Harvey P. Dale, Jan 06 2013 *)
Select[Range[350],SequenceCount[IntegerDigits[5^#],IntegerDigits[#]]>0&] (* Harvey P. Dale, Dec 27 2024 *)