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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A134339 a(n) = product of the positive "non-isolated divisors" of (2n). A divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n. 1

%I

%S 2,2,6,2,2,24,2,2,6,40,2,24,2,2,180,2,2,24,2,40,252,2,2,24,2,2,6,112,

%T 2,720,2,2,6,2,2,1728,2,2,6,40,2,1008,2,2,16200,2,2,24,2,40,6,2,2,24,

%U 220,112,6,2,2,720,2,2,252,2,2,3168,2,2,6,40,2,1728,2,2,180,2,2,3744,2,40,6

%N a(n) = product of the positive "non-isolated divisors" of (2n). A divisor, k, of n is non-isolated if (k-1) or (k+1) also divides n.

%C No odd integer has any non-isolated divisors.

%F a(n) = A007955(2n) / A134338(2n). - Chandler

%e The divisors of 2*10 = 20 are 1,2,4,5,10,20. Of these, 1,2,4,5 are the non-isolated divisors. So a(10) = 1*2*4*5 = 40.

%Y Cf. A134338.

%K nonn

%O 1,1

%A _Leroy Quet_, Oct 21 2007

%E Extended by _Ray Chandler_, Jun 24 2008

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 20 09:50 EDT 2019. Contains 321345 sequences. (Running on oeis4.)