OFFSET
0,2
COMMENTS
Main diagonal of array defined by m(1,j)=j; m(i,1)=i and m(i,j)=m(i-1,j)+4*m(i-1,j-1) - Benoit Cloitre, Jun 13 2003
LINKS
FORMULA
a(n) = 10*a(n-1)-25*a(n-2), a(0)=1, a(1)=6.
a(n) = (n+5)*5^(n-1).
G.f.: (1-4x)/(1-5x)^2.
a(n) = A079027(n), n>0. - R. J. Mathar, Sep 18 2008
From Amiram Eldar, Jan 19 2021: (Start)
Sum_{n>=0} 1/a(n) = 15625*log(5/4) - 41825/12.
Sum_{n>=0} (-1)^n/a(n) = 15625*log(6/5) - 34175/12. (End)
MATHEMATICA
LinearRecurrence[{10, -25}, {1, 6}, 30] (* Harvey P. Dale, Jan 20 2014 *)
PROG
(PARI) a(n)=if(n, ([0, 1; -25, 10]^n*[1; 6])[1, 1], 1) \\ Charles R Greathouse IV, Oct 07 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Mar 07 2003
STATUS
approved