OFFSET
1,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
FORMULA
For n >= 2, a(n) also is Sum_{k=1 .. n} b(k), where b(k) is the number of terms of {a(j)} which divide k.
EXAMPLE
a(5)=8 because floor(5/1) + floor(5/2) + floor(5/4) + floor(5/7) = 5 + 2 + 1 + 0 = 8.
MAPLE
a[1]:=1: for n from 2 to 70 do a[n]:=sum(floor(n/a[k]), k=1..n-1): od: seq(a[n], n=1..70); # Emeric Deutsch, Apr 01 2006
MATHEMATICA
s={1}; Do[ AppendTo[s, Sum[Floor[n/s[[k]]], {k, n-1}] ] , {n, 2, 63}]; s (* James C. McMahon, Aug 21 2024 *)
PROG
(Haskell)
a116478 n = a116478_list !! (n-1)
a116478_list = 1 : f [2..] [1] where
f (x:xs) ys = y : f xs (y:ys) where y = sum $ map (div x) ys
-- Reinhard Zumkeller, Jul 18 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Mar 18 2006
EXTENSIONS
More terms from Emeric Deutsch, Apr 01 2006
STATUS
approved