OFFSET
1,2
EXAMPLE
a(3) = 17 since 17! is the least factorial to start with digit "3" when written in base 5. a(5) = 6 since 5 = 10[5] (i.e. written in base 5) and 6! = 720 = 625 + 75 + 20 = 10340[5] is the smallest factorial to start with digits "10" when written in base 5.
PROG
(PARI) A155895(n)={ local( F=1, k=1 ); while( F\1!=n, F*=k++; while( F>=n+1, F/=5)); k}
CROSSREFS
KEYWORD
base,nonn
AUTHOR
M. F. Hasler, Feb 01 2009
STATUS
approved