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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

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