OFFSET
0,2
COMMENTS
Sum of n-th row of triangle of powers of 6: 1; 6 1 6; 36 6 1 6 36; 216 36 6 1 6 36 216; ...
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (7,-6).
FORMULA
G.f.: (1+6*x)/((1-x)*(1-6*x)).
a(n) = 7*a(n-1) - 6*a(n-2) for n>1, a(0)=1, a(1)=13.
a(n) = 6*a(n-1) + 7 for n>0, a(0)=1.
a(n) = A026567(2*n). - Philippe Deléham, Feb 24 2014
EXAMPLE
a(0) = 1;
a(1) = 6 + 1 + 6 = 13;
a(2) = 36 + 6 + 1 + 6 + 36 = 85;
a(3) = 216 + 36 + 6 + 1 + 6 + 36 + 216 = 517; etc.
MATHEMATICA
Table[(2 6^(n + 1) - 7)/5, {n, 0, 20}] (* Vincenzo Librandi, Feb 25 2014 *)
PROG
(Magma) [(2*6^(n+1) - 7) / 5: n in [0..30]]; // Vincenzo Librandi, Feb 25 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Feb 23 2014
STATUS
approved