The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 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 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.

Last modified December 2 14:43 EST 2021. Contains 349445 sequences. (Running on oeis4.)