OFFSET
0,1
COMMENTS
After 4, these numbers are the third column of the rectangular array in A238475.
LINKS
FORMULA
G.f.: (4 - 3*x) / ((1 - x)*(1 - 4*x)).
a(n) = 5*a(n-1) - 4*a(n-2) for n > 1.
a(n) = 4*a(n-1) + 1 for n > 0.
a(n) = (13*4^n -1)/3, for n >= 0. - Wolfdieter Lang, Sep 16 2021
MATHEMATICA
Table[(4^(n + 1) + (4^n - 1) / 3), {n, 0, 30}]
PROG
(Magma) [4^(n+1)+(4^n-1)/3: n in [0..30]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 09 2020
STATUS
approved