A155892 Least positive integer such that a(n)! starts with n, both written in base 3.

1, 2, 12, 5, 13, 3, 19, 4, 31, 18, 12, 21, 5, 33, 17, 13, 34, 8, 38, 7, 19, 92, 24, 4, 11, 6, 46, 39, 31, 22, 18, 77, 12, 55, 32, 75, 21, 52, 74, 5, 15, 33, 61, 122, 166, 17, 47, 13, 65, 54, 49, 148, 34, 71, 8, 117, 107, 60, 38, 51, 10, 7, 111, 25, 19, 92, 123, 128, 29, 24, 56, 99

Offset

1,2

Links

Table of n, a(n) for n=1..72.

Example

a(4) = 5 since 4 = 11[3] (i.e. written in base 2) and 5! = 11110[3] is the least factorial to have 11 as most significant digits in base 3.

Prog

(PARI) A155892(n)={ local( F=1, k=1 ); while( F\1!=n, F*=k++; while( F>=n+1, F/=3 )); k}

Crossrefs

Cf. A155891, A018799, A076219.

Sequence in context: A191249 A333544 A005760 * A286480 A286256 A239111

Adjacent sequences: A155889 A155890 A155891 * A155893 A155894 A155895

Keyword

base,nonn

Author

M. F. Hasler, Feb 01 2009

Status

approved