A141032 a(n) = 4*(16^n-1)/15.

0, 4, 68, 1092, 17476, 279620, 4473924, 71582788, 1145324612, 18325193796, 293203100740, 4691249611844, 75059993789508, 1200959900632132, 19215358410114116, 307445734561825860, 4919131752989213764, 78706108047827420228, 1259297728765238723652

Offset: 0

Author

Paul Curtz, Jul 30 2008

Keywords

• nonn
• easy

Comments

The sequence of last digits, a(n) mod 10, is periodic with period length 5: repeat 0, 4, 8, 2, 6.

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..200
• Index entries for linear recurrences with constant coefficients, signature (17,-16)

Programs

Magma

[(4/15)*(16^n-1): n in [0..25]]; // Vincenzo Librandi, May 25 2011

Maple

A141032:=n->4*(16^n-1)/15; seq(A141032(n), n=0..30); # Wesley Ivan Hurt, Mar 26 2014

Mathematica

s=0;lst={s};Do[s+=2^n;AppendTo[lst, s], {n, 2, 5!, 4}];lst (* Vladimir Joseph Stephan Orlovsky, Nov 07 2008 *)

Formula

a(n) = (A141060(n)-3)/10.

a(n) = 16*a(n-1)+4.

a(n) = 4*A131865(n-1).

a(n+1)-a(n) = A013709(n).

G.f.: 4*x / ( (16*x-1)*(x-1) ). - R. J. Mathar, Jul 02 2011

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Nov 07 2008