OFFSET
0,1
COMMENTS
An Engel expansion of 4/5 to the base 4 as defined in A181565, with the associated series expansion 4/5 = 4/6 + 4^2/(6*21) + 4^3/(6*21*81) + 4^4/(6*21*81*321) + ... . Cf. A136412 and A140660. - Peter Bala, Oct 29 2013
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (5,-4).
FORMULA
a(n) = 3*A136412(n).
a(n) = 4*a(n-1)-3.
a(n) = 5*a(n-1)-4*a(n-2).
G.f.: 3*(2-3*x)/((1-x)*(1-4*x)). - Bruno Berselli, Nov 04 2011
MATHEMATICA
5*4^Range[0, 30]+1 (* or *) LinearRecurrence[{5, -4}, {6, 21}, 30] (* Harvey P. Dale, Oct 19 2024 *)
PROG
(Magma) [5*4^n+1: n in [0..30]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 04 2011
STATUS
approved