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A141032
a(n) = 4*(16^n-1)/15.
3
0, 4, 68, 1092, 17476, 279620, 4473924, 71582788, 1145324612, 18325193796, 293203100740, 4691249611844, 75059993789508, 1200959900632132, 19215358410114116, 307445734561825860, 4919131752989213764, 78706108047827420228, 1259297728765238723652
OFFSET
0,2
COMMENTS
The sequence of last digits, a(n) mod 10, is periodic with period length 5: repeat 0, 4, 8, 2, 6.
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
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 *)
PROG
(Magma) [(4/15)*(16^n-1): n in [0..25]]; // Vincenzo Librandi, May 25 2011
CROSSREFS
Sequence in context: A221336 A339787 A323276 * A156084 A362730 A000658
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Jul 30 2008
EXTENSIONS
More terms from Vladimir Joseph Stephan Orlovsky, Nov 07 2008
STATUS
approved