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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A046098 Numbers n such that central binomial coefficient C(n, floor[n/2]) is squarefree. 19
0, 1, 2, 3, 4, 5, 7, 8, 11, 17, 19, 23, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

No other n < 10^8. - T. D. Noe, Apr 06 2007

LINKS

Table of n, a(n) for n=1..13.

Eric Weisstein's World of Mathematics, Central Binomial Coefficient

Eric Weisstein's World of Mathematics, Squarefree

MATHEMATICA

Select[Range[0, 100], SquareFreeQ[Binomial[#, Floor[#/2]]]&] (* Harvey P. Dale, Mar 11 2011 *)

PROG

(PARI) is(n)=issquarefree(binomial(n, n\2)) \\ Charles R Greathouse IV, Jul 16, 2011

CROSSREFS

Cf. A001405.

Cf. A056651 (cubefree central binomial coefficients).

Sequence in context: A238484 A241340 A111795 * A258085 A247350 A057484

Adjacent sequences:  A046095 A046096 A046097 * A046099 A046100 A046101

KEYWORD

nonn,hard

AUTHOR

Eric W. Weisstein

EXTENSIONS

0 added by T. D. Noe, Mar 06 2014

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 10 23:13 EST 2016. Contains 279021 sequences.