OFFSET
0,1
COMMENTS
A194079(n) gives number of digits of a(n).
FORMULA
a(0) = 5; a(k+1) = floor(a(k)/2) * ceiling(a(k)/2).
a(n+1) = A002620(a(n)), a(0) = 5. - Reinhard Zumkeller, Oct 12 2011
EXAMPLE
6 = 2*3; 9 = 3*3; 20 = 4*5; ...
MATHEMATICA
a=5; a=Table[a=Ceiling[a/2]*Floor[a/2], {n, 0, 10}] (* Vladimir Joseph Stephan Orlovsky, Apr 13 2010 *)
NestList[Floor[#/2]Ceiling[#/2]&, 5, 10] (* Harvey P. Dale, Jul 10 2012 *)
PROG
(Haskell)
a014980 n = a014980_list !! n
a014980_list = iterate a002620 5
-- Reinhard Zumkeller, Oct 12 2011
(Python)
from itertools import accumulate
def f(an, _): return (an//2)*((an+1)//2)
print(list(accumulate([5]*11, f))) # Michael S. Branicky, May 06 2021
CROSSREFS
KEYWORD
nonn,nice,easy
AUTHOR
Colin Sandon (sandon(AT)together.net)
EXTENSIONS
More terms from James A. Sellers, Feb 05 2000
STATUS
approved