A024026 a(n) = 3^n - n^3.

1, 2, 1, 0, 17, 118, 513, 1844, 6049, 18954, 58049, 175816, 529713, 1592126, 4780225, 14345532, 43042625, 129135250, 387414657, 1162254608, 3486776401, 10460343942, 31381048961, 94143166660, 282429522657, 847288593818

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200

Programs

Magma

[3^n-n^3: n in [0..30]]; // Vincenzo Librandi, May 14 2011

Maple

seq(3^n-n^3, n=0..25); # Zerinvary Lajos, Jul 01 2007

Mathematica

lst={}; Do[AppendTo[lst,(3^n-n^3)],{n,0,5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jan 15 2009 *)

PARI

a(n)=3^n-n^3 \\ Charles R Greathouse IV, Jul 02 2013

Formula

G.f.: (-1 + 5*x - 5*x^2 - 7*x^3 - 4*x^4)/((3*x-1)*(x-1)^4). - Maksym Voznyy (voznyy(AT)mail.ru), Aug 14 2009