OFFSET
2,1
LINKS
Colin Barker, Table of n, a(n) for n = 2..1000
Index entries for linear recurrences with constant coefficients, signature (7,-14,8).
FORMULA
a(n) = 2*(2^(n-1) + 2)*(2^(n-1) - 1) for n>=3. - Nathaniel Johnston, May 30 2011
a(0)=11, a(1)=36, a(2)=140, a(3)=540, a(n)=7*a(n-1)-14*a(n-2)+8*a(n-3). - Harvey P. Dale, Jun 10 2011
G.f.: x^2*(11 - 41*x + 42*x^2 - 24*x^3) / ((1 - x)*(1 - 2*x)*(1 - 4*x)). - Colin Barker, Jan 26 2018
MATHEMATICA
Join[{11}, LinearRecurrence[{7, -14, 8}, {36, 140, 540}, 40]] (* Harvey P. Dale, Jun 10 2011 *)
PROG
(PARI) a(n)=if(n<3, 11, 2*(2^(n-1) + 2)*(2^(n-1) - 1)) \\ Charles R Greathouse IV, Jun 01 2011
(PARI) Vec(x^2*(11 - 41*x + 42*x^2 - 24*x^3) / ((1 - x)*(1 - 2*x)*(1 - 4*x)) + O(x^40)) \\ Colin Barker, Jan 26 2018
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
Juri-Stepan Gerasimov, May 29 2011
EXTENSIONS
a(11)-a(27) and recurrence from Charles R Greathouse IV, May 29 2011
STATUS
approved