OFFSET
0,1
COMMENTS
Related to Reverse and Add trajectory of 318 in base 4: A075153(6*n) = 3*a(n).
lim_{n -> infinity} a(n)/a(n-1) = 16.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..500
Index entries for linear recurrences with constant coefficients, signature (21, -84, 64).
FORMULA
a(n) = (1280*16^n + 940*4^n - 15)/3 for n > 0.
G.f.: (106 + 5849*x - 46436*x^2 + 40256*x^3)/((1-x)*(1-4*x)*(1-16*x)).
From G. C. Greubel, May 28 2016: (Start)
a(n) = 21*a(n-1) - 84*a(n-2) + 64*a(n-3).
E.g.f.: (1/3)*(-15*exp(x) + 940*exp(4*x) + 1280*exp(16*x)) - 629. (End)
MATHEMATICA
Join[{106}, LinearRecurrence[{21, -84, 64}, {8075, 114235, 1767675}, 20]] (* Harvey P. Dale, Jun 07 2012 *)
PROG
(PARI) m=15; v=concat([106, 8075, 114235], vector(m-3)); for(n=4, m, v[n]=20*v[n-1]-64*v[n-2]-225); v
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Klaus Brockhaus, Oct 27 2009
STATUS
approved