OFFSET
0,6
EXAMPLE
a(5) = 2 because 5!! = 5*3*1 = 15.
MAPLE
SFACT:= proc(n) local i, j, k; for k from 1 by 1 to n do i:=k; j:=k-2; while j >0 do i:=i*j; j:=j-2; od: j:=0; while i>0 do i:=trunc(i/10); j:=j+1; od; print(j) od; end: SFACT(100);
# second Maple program:
a:= n-> length(doublefactorial(n)):
seq(a(n), n=0..76); # Alois P. Heinz, Sep 28 2023
MATHEMATICA
IntegerLength[Range[80]!!] (* Harvey P. Dale, Mar 23 2018 *)
CROSSREFS
KEYWORD
easy,nonn,base
AUTHOR
Paolo P. Lava and Giorgio Balzarotti, Jan 08 2007
EXTENSIONS
a(0)=1 prepended by Georg Fischer, Sep 28 2023
STATUS
approved