OFFSET
0,2
COMMENTS
The e.g.f. given below is Sum_{m=0..1} A075513(2,m)*exp(7*(m+1)*x).
LINKS
Index entries for linear recurrences with constant coefficients, signature (21, -98).
FORMULA
a(n) = -7^n + 2*14^n.
G.f.: 1/((1-7*x)*(1-14*x)).
E.g.f.: (d^2/dx^2)(((exp(7*x)-1)/7)^2)/2! = -exp(7*x) + 2*exp(14*x).
a(0)=1, a(1)=21, a(n) = 21a(n-1) - 98a(n-2). - Harvey P. Dale, Apr 30 2011
MATHEMATICA
Table[-7^n+2 14^n, {n, 0, 20}] (* or *) LinearRecurrence[{21, -98}, {1, 21}, 20] (* Harvey P. Dale, Apr 30 2011 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Oct 02 2002
STATUS
approved