OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,0,0,0,0,0,0,-1).
FORMULA
The generating function is f such that: f(z)=1/(1-2*z+z^8). Recurrence relation: a(n+8)=2*a(n+7)-a(n). General term: a(n) = Sum_{j=0..floor(n/(k+1))} ((-1)^j*binomial(n-k*j,n-(k+1)*j)*2^(n-(k+1)*j)) with k=7.
EXAMPLE
a(4) = binomial(4,4)*2^4 = 16.
a(9) = binomial(9,9)*2^9 - binomial(2,1)*2^1 = 512 - 4 = 508.
MAPLE
k:=7:taylor(1/(1-2*z+z^(k+1)), z=0, 30); for k from 0 to 20 do for n from 0 to 30 do b(n):=sum((-1)^j*binomial(n-k*j, n-(k+1)*j)*2^(n-(k+1)*j), j=0..floor(n/(k+1))):od:k: seq(b(n), n=0..30):od;
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Richard Choulet, Jan 31 2010
STATUS
approved