OFFSET
1,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (21,273,-1092,-1820,1092,273,-21,-1).
FORMULA
a(n) = A010048(n+7, 7) =: Fibonomial(n+7, 7).
G.f.: 1/p(8, n) with p(8, n) = 1 - 21*x - 273*x^2 + 1092*x^3 + 1820*x^4 - 1092*x^5 - 273*x^6 + 21*x^7 + x^8 = (1 + x - x^2) * (1 - 4*x - x^2) * (1 + 11*x - x^2) * (1 - 29*x - x^2) (n=8 row polynomial of signed Fibonomial triangle A055870; see this entry for Knuth and Riordan references).
a(n) = 29*a(n-1) + a(n-2) + ((-1)^n) * A001657(n), n >= 2, a(0)=1, a(1)=21.
MAPLE
with(combinat):
a:= n-> 1/3120 *fibonacci(n) *fibonacci(n+1) *fibonacci(n+2) *fibonacci(n+3) *fibonacci(n+4) *fibonacci(n+5) *fibonacci(n+6):
seq(a(n), n=1..17); # Zerinvary Lajos, Oct 07 2007
MATHEMATICA
(Times@@@Partition[Fibonacci[Range[30]], 7, 1])/3120 (* Harvey P. Dale, Apr 10 2011 *)
PROG
(Magma) [ &*[Fibonacci(n+k): k in [0..6]]/3120: n in [1..16] ]; // Bruno Berselli, Apr 11 2011
(PARI) b(n, k)=prod(j=1, k, fibonacci(n+j)/fibonacci(j));
vector(20, n, b(n-1, 7)) \\ Joerg Arndt, May 08 2016
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Jul 10 2000
STATUS
approved