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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A039593 Number of unitary divisors of central binomial coefficients. 3
1, 2, 2, 4, 4, 4, 4, 8, 8, 8, 16, 16, 16, 16, 16, 32, 32, 32, 32, 32, 64, 64, 64, 64, 64, 64, 64, 64, 128, 128, 128, 256, 256, 256, 512, 512, 512, 512, 1024, 1024, 1024, 1024, 1024, 1024, 512, 512, 1024, 1024, 1024, 1024, 1024, 1024, 1024, 1024, 4096, 4096 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

As in A034444, all terms are powers of 2.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A034444(A001405(n)) = 2^A034973(n).

EXAMPLE

At n=5, the central binomial coefficient is 10, having 4 divisors, each of which is unitary, so a(5)=4.

MATHEMATICA

a[n_] := 2^PrimeNu[Binomial[n, Floor[n/2]]]; Array[a, 56] (* Amiram Eldar, Oct 06 2019 *)

CROSSREFS

Cf. A001405, A034444, A034973.

Sequence in context: A279170 A292254 A292942 * A327649 A265529 A292597

Adjacent sequences:  A039590 A039591 A039592 * A039594 A039595 A039596

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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 December 11 02:16 EST 2019. Contains 329910 sequences. (Running on oeis4.)