login
a(0) = 0 and a(n) = (5*(-4)^n + 16*(-1)^n + 9*4^n)/240 for n >= 1.
0

%I #19 Aug 30 2022 06:40:56

%S 0,0,1,1,15,17,239,273,3823,4369,61167,69905,978671,1118481,15658735,

%T 17895697,250539759,286331153,4008636143,4581298449,64138178287,

%U 73300775185,1026210852591,1172812402961,16419373641455,18764998447377

%N a(0) = 0 and a(n) = (5*(-4)^n + 16*(-1)^n + 9*4^n)/240 for n >= 1.

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-1,16,16).

%F From _Colin Barker_, Dec 03 2012: (Start)

%F a(n) = (5*(-4)^n + 16*(-1)^n + 9*4^n)/240 for n>0.

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

%t a[n_] := If[n == 0, 1, (5(-4)^n + 16(-1)^n + 9*4^n) / 240];

%t a /@ Range[0, 25] (* _Jean-François Alcover_, Mar 30 2021 *)

%Y Cf. A112627.

%K nonn,easy

%O 0,5

%A _Roger L. Bagula_, Jan 31 2006

%E New name (using _Colin Barker_'s formula) from _Joerg Arndt_, Aug 30 2022