login
a(n) = n*(11*n+1)/2.
12

%I #32 Aug 24 2017 16:34:44

%S 0,6,23,51,90,140,201,273,356,450,555,671,798,936,1085,1245,1416,1598,

%T 1791,1995,2210,2436,2673,2921,3180,3450,3731,4023,4326,4640,4965,

%U 5301,5648,6006,6375,6755,7146,7548,7961,8385,8820,9266,9723,10191,10670,11160

%N a(n) = n*(11*n+1)/2.

%C Essentially identical to A026817. - _R. J. Mathar_, May 28 2008

%H G. C. Greubel, <a href="/A022269/b022269.txt">Table of n, a(n) for n = 0..5000</a>

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

%F a(n) = A110449(n, 5) for n>4.

%F a(n) = 11*n + a(n-1) - 5 with n>0, a(0)=0. - _Vincenzo Librandi_, Aug 04 2010

%F G.f.: x*(6 + 5*x)/(1 - x)^3. - _Philippe Deléham_, Mar 27 2013

%F a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) with n>2, a(0)=0, a(1)=6, a(2)=23. - _Philippe Deléham_, Mar 27 2013

%F a(n) = A218530(11*n+5).

%F a(n) = A000217(6*n) - A000217(5*n). - _Bruno Berselli_, Oct 13 2016

%F E.g.f.: (x/2)*(11*x + 12)*exp(x). - _G. C. Greubel_, Aug 24 2017

%t Table[n*(11*n + 1)/2, {n,0,50}] (* _G. C. Greubel_, Aug 24 2017 *)

%o (PARI) a(n)=n*(11*n+1)/2 \\ _Charles R Greathouse IV_, Jun 17 2017

%Y Cf. A110449.

%Y Cf. similar sequences listed in A022289.

%K nonn,easy

%O 0,2

%A _N. J. A. Sloane_