OFFSET
0,2
LINKS
FORMULA
a(n) = ((1+sqrt(5))*(6+sqrt(5))^n+(1-sqrt(5))*(6-sqrt(5))^n)/2.
G.f.: (1-x)/(1-12*x+31*x^2).
MATHEMATICA
LinearRecurrence[{12, -31}, {1, 11}, 20] (* Harvey P. Dale, Apr 15 2019 *)
PROG
(Magma) [ n le 2 select 10*n-9 else 12*Self(n-1)-31*Self(n-2): n in [1..20] ];
(PARI) a(n)=([0, 1; -31, 12]^n*[1; 11])[1, 1] \\ Charles R Greathouse IV, May 30 2026
CROSSREFS
KEYWORD
nonn,easy,changed
AUTHOR
Klaus Brockhaus, Jul 21 2009
STATUS
approved
