A016839 a(n) = (4*n+3)^3.

27, 343, 1331, 3375, 6859, 12167, 19683, 29791, 42875, 59319, 79507, 103823, 132651, 166375, 205379, 250047, 300763, 357911, 421875, 493039, 571787, 658503, 753571, 857375, 970299, 1092727, 1225043

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Ivan Panchenko, Table of n, a(n) for n = 0..200
• Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Programs

Mathematica

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

PARI

a(n) = (4*n+3)^3; \\ Altug Alkan, Dec 03 2015

Formula

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

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