OFFSET
1,2
EXAMPLE
a(6)=9 since m!!<6! for m<9, while 9!!>=6!.
MATHEMATICA
Module[{df=Table[{i, i!!}, {i, 200}]}, Transpose[Table[SelectFirst[df, #[[2]]>= n!&], {n, 100}]][[1]]] (* Harvey P. Dale, Nov 05 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Giovanni Resta, Feb 16 2006
STATUS
approved