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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A024172 Integer part of ((3rd elementary symmetric function of 1,2,..,n)/(2nd elementary symmetric function of 1,2,...,n)). 1
0, 0, 1, 2, 4, 6, 8, 10, 13, 16, 20, 24, 28, 33, 38, 43, 48, 54, 60, 67, 74, 81, 89, 97, 105, 113, 122, 131, 141, 151, 161, 172, 183, 194, 205, 217, 229, 242, 255, 268, 282, 296, 310, 324 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

LINKS

Ivan Neretin, Table of n, a(n) for n = 2..10000

FORMULA

a(n) = floor( A001303(n-2)/A000914(n-1) ). - R. J. Mathar, Sep 15 2009

Empirical g.f.: x^4*(x^4-x^3+x^2-x+1)*(x^5-x^3-x^2-x-1) / ((x-1)^3*(x^2+x+1)*(x^6+x^3+1)). - Colin Barker, Aug 16 2014

a(n) = floor((1/2)*(n - 2)*n*(n + 1)/(3*n + 2)).

EXAMPLE

a(3) = floor(6/11) = 0; a(4) = floor(50/35) = 1. - R. J. Mathar, Sep 15 2009

MAPLE

seq(floor((1/2)*n*(n-2)*(n+1)/(3*n+2)), n=2..50); # Muniru A Asiru, May 19 2018

MATHEMATICA

Table[Floor[1/2 (n - 2) n (n + 1)/ (3 n + 2)], {n, 2, 45}] (* Ivan Neretin, May 19 2018 *)

PROG

(GAP) List([2..50], n->Int((1/2)*n*(n-2)*(n+1)/(3*n+2))); # Muniru A Asiru, May 19 2018

CROSSREFS

Sequence in context: A302648 A269746 A056827 * A233735 A085577 A121832

Adjacent sequences:  A024169 A024170 A024171 * A024173 A024174 A024175

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Offset set to 2 by R. J. Mathar, Sep 15 2009

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 October 22 08:00 EDT 2019. Contains 328315 sequences. (Running on oeis4.)