login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A168386 Arithmetic derivative of the double factorial of n. 2

%I

%S 0,0,1,1,12,8,112,71,1472,1269,17408,14904,270336,204147,4199424,

%T 4143285,87834624,72462870,1797783552,1411253955,40414740480,

%U 36183623805,937430876160,845972658090,26095323709440,24311657884500,707908274749440,869872809558375

%N Arithmetic derivative of the double factorial of n.

%H Alois P. Heinz, <a href="/A168386/b168386.txt">Table of n, a(n) for n = 0..800</a>

%F a(n) = A003415(A006882(n)). - _R. J. Mathar_, Nov 26 2009

%p A003415 := proc(n) local pfs ; if n <= 1 then 0 ; else pfs := ifactors(n)[2] ; n*add(op(2,p)/op(1,p),p=pfs) ; fi; end proc:

%p A168386 := proc(n) A003415(doublefactorial(n)) ; end proc:

%p seq(A168386(n),n=1..80) ; # _R. J. Mathar_, Nov 26 2009

%p # second Maple program:

%p d:= n-> n*add(i[2]/i[1], i=ifactors(n)[2]):

%p a:= proc(n) option remember;

%p `if`(n<2, 0, a(n-2)*n+doublefactorial(n-2)*d(n))

%p end:

%p seq(a(n), n=0..40); # _Alois P. Heinz_, Jun 06 2015

%Y Cf. A003415, A068311.

%K easy,nonn

%O 0,5

%A _Paolo P. Lava_ and _Giorgio Balzarotti_, Nov 24 2009

%E Program replaced by a structured program - _R. J. Mathar_, Nov 26 2009

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 4 05:11 EST 2016. Contains 278748 sequences.