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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A309183 (1/4) times the number of n-member subsets of [4n] whose elements sum to a multiple of n. 2

%I

%S 1,3,19,115,776,5601,42288,328755,2615104,21191128,174303163,

%T 1451430673,12211799224,103655906784,886568153744,7633233556275,

%U 66105170315084,575445689884848,5032380942945322,44191451788247640,389514699013012242,3444925385161998521

%N (1/4) times the number of n-member subsets of [4n] whose elements sum to a multiple of n.

%C Also (1/3) times the number of n-member subsets of [4n-1] whose elements sum to a multiple of n.

%H Alois P. Heinz, <a href="/A309183/b309183.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = 1/(4n) * Sum_{d|n} binomial(4d,d)*(-1)^(n+d)*phi(n/d).

%p with(numtheory):

%p a:= n-> add(binomial(4*d, d)*(-1)^(n+d)*

%p phi(n/d), d in divisors(n))/(4*n):

%p seq(a(n), n=1..25);

%Y Column k=4 of A309148.

%K nonn

%O 1,2

%A _Alois P. Heinz_, Jul 15 2019

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 September 21 05:02 EDT 2021. Contains 347596 sequences. (Running on oeis4.)