A016839 - OEIS

%I #18 Jun 28 2020 02:51:30

%S 27,343,1331,3375,6859,12167,19683,29791,42875,59319,79507,103823,

%T 132651,166375,205379,250047,300763,357911,421875,493039,571787,

%U 658503,753571,857375,970299,1092727,1225043

%N a(n) = (4*n+3)^3.

%H Ivan Panchenko, <a href="/A016839/b016839.txt">Table of n, a(n) for n = 0..200</a>

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

%F G.f.: ( 27+235*x+121*x^2+x^3 ) / (x-1)^4 . - _R. J. Mathar_, Dec 03 2015

%F Sum_{n>=0} 1/a(n) = 7*zeta(3)/16 - Pi^3/64. - _Amiram Eldar_, Jun 28 2020

%t (4*Range[0,30]+3)^3 (* or *) LinearRecurrence[{4,-6,4,-1},{27,343,1331,3375},30] (* _Harvey P. Dale_, Jul 21 2018 *)

%o (PARI) a(n) = (4*n+3)^3; \\ _Altug Alkan_, Dec 03 2015

%K nonn,easy

%O 0,1

%A _N. J. A. Sloane_.