OFFSET
1,1
LINKS
Ralf Stephan, Some divide-and-conquer sequences with (relatively) simple ordinary generating functions, 2004.
Ralf Stephan, Table of generating functions.
FORMULA
a(n) = 2*n*A001511(n).
G.f.: Sum_{k>=0} 2^(k+1)*x^2^k/(1-x^2^k)^2. - Ralf Stephan, Jun 07 2003
a(n) = 2 * A091512(n). - Alois P. Heinz, Oct 14 2021
Sum_{k=1..n} a(k) ~ 2*n^2. - Amiram Eldar, Sep 13 2024
MAPLE
a:= 2*n*padic[ordp](2*n, 2):
seq(a(n), n=1..61); # Alois P. Heinz, Oct 14 2021
MATHEMATICA
Table[ Part[ Flatten[ FactorInteger[n^n]], 2], {n, 2, 124, 2}]
PROG
(PARI) a(n) = n<<=1; n*valuation(n, 2); \\ Kevin Ryde, Oct 14 2021
(Julia)
function A069895List(length)
a = zeros(Int, length)
for n in 1:length a[n] = 2 * (isodd(n) ? n : n + a[div(n, 2)]) end
a end
A069895List(61) |> println # Peter Luschny, Oct 16 2021
(Python)
def A069895(n): return n*(n&-n).bit_length()<<1 # Chai Wah Wu, Jul 11 2022
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Labos Elemer, Apr 10 2002
STATUS
approved