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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A081393 a(n) is the smallest x such that number of non-unitary prime divisors of central binomial coefficient, A000984(x)=C(2x,x) equals n. 2
1, 3, 5, 14, 48, 74, 182, 314, 480, 774, 960, 1321, 1323, 1670, 3121, 3455, 3457, 3472, 3462, 3469, 8203, 9991 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..21.

FORMULA

a(n) = Min{x; A081387(x)=n}.

EXAMPLE

n=5: a(5)=74, C(148,74) has 5 non-unitary prime divisors: {2,3,5,7,11} and 74 is the smallest.

CROSSREFS

Cf. A081387, A081394, A081395.

Sequence in context: A230585 A006395 A078718 * A338368 A129326 A167553

Adjacent sequences:  A081390 A081391 A081392 * A081394 A081395 A081396

KEYWORD

nonn,more

AUTHOR

Labos Elemer, Mar 27 2003

EXTENSIONS

a(11)-a(21) from Michel Marcus, Sep 01 2019

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 January 19 16:16 EST 2021. Contains 340270 sequences. (Running on oeis4.)