This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A162256 a(n) = (2*n^3 + 5*n^2 - 3*n)/2. 2

%I

%S 2,15,45,98,180,297,455,660,918,1235,1617,2070,2600,3213,3915,4712,

%T 5610,6615,7733,8970,10332,11825,13455,15228,17150,19227,21465,23870,

%U 26448,29205,32147,35280,38610,42143,45885,49842,54020,58425,63063,67940

%N a(n) = (2*n^3 + 5*n^2 - 3*n)/2.

%C Row sums from A154680.

%H Vincenzo Librandi, <a href="/A162256/b162256.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).

%F From _Vincenzo Librandi_, Mar 04 2012: (Start)

%F G.f.: x*(2 + 7*x - 3*x^2)/(1-x)^4.

%F a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)

%t LinearRecurrence[{4,-6,4,-1}, {2, 15, 45, 98}, 50] (* or *) CoefficientList[Series[(2+7*x-3*x^2)/(1-x)^4,{x,0,39}],x] (* _Vincenzo Librandi_, Mar 04 2012 *)

%o (PARI) n*(5*n-3)/2+n^3 \\ _Charles R Greathouse IV_, Jan 11 2012

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Jun 29 2009

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.

Last modified February 16 21:59 EST 2019. Contains 320200 sequences. (Running on oeis4.)