A181509 - OEIS

%I #23 Jun 17 2017 03:03:14

%S 2,6,56,152,296,488,728,1016,1352,1736,2168,2648,3176,3752,4376,5048,

%T 5768,6536,7352,8216,9128,10088,11096,12152,13256,14408,15608,16856,

%U 18152,19496,20888,22328,23816,25352,26936,28568,30248,31976,33752

%N a(1) = 2, a(n) = (n-th-even n^3) - (sum of previous terms)

%H Vincenzo Librandi, <a href="/A181509/b181509.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).

%F a(n) = 56-72*n+24*n^2, n>2. a(n) = (2*n-2)^3-sum_{i=1..n-1} a(i). [From R. J. Mathar, Nov 01 2010]

%F For n>2, a(1)=56, a(2)=152, a(3)=296, a(n)=3*a(n-1)-3*a(n-2)+a(n-3) [From Harvey P. Dale, May 05 2011]

%F G.f.: 2*x*(22*x^2+x^4+1)/(1-x)^3. - R. J. Mathar, Aug 26 2011

%F a(n)=8*A003215(n-2) for n>2. - _J. M. Bergot_, Aug 21 2013

%t Join[{2,6},Table[56-72n+24n^2,{n,3,42}]] (* or *) Join[{2,6}, LinearRecurrence[{3,-3,1},{56,152,296},40]] (* _Harvey P. Dale_, May 05 2011 *)

%Y Cf. A000578.

%K easy,nonn

%O 1,1

%A _Giovanni Teofilatto_, Oct 25 2010

%E Corrected (replaced 2 and 4 by a 6 = 8-2) by _R. J. Mathar_, Nov 01 2010