OFFSET
0,4
COMMENTS
LINKS
T. D. Noe, Table of n, a(n) for n = 0..10000
FORMULA
Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = -1 + Sum_{p prime} 1/(p*(p-1)) = A136141 - 1 = -0.226843... . - Amiram Eldar, Dec 08 2023
MAPLE
with(numtheory);
A168036:=proc(q)
local n, p;
for n from 0 to q do
print(n*add(op(2, p)/op(1, p), p=ifactors(n)[2])-n); od; end:
A168036(1000); # Paolo P. Lava, Nov 05 2012
MATHEMATICA
np[k_] := Module[{f, n, m, p}, If[k < 2, np[k] = 0; Return[0], If[PrimeQ[k], np[k] = 1; Return[1], f = FactorInteger[k, 2]; m = f[[1, 1]]; n = k/m; p = m np[n] + n np[m]; np[k] = p; Return[p]]]];
Table[np[n] - n, {n, 0, 100}] (* Robert Price, Mar 14 2020 *)
PROG
(Haskell)
a168036 n = a003415 n - n -- Reinhard Zumkeller, May 22 2015
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Paolo P. Lava, Nov 17 2009
STATUS
approved