OFFSET
0,3
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).
FORMULA
G.f.: 7*x^2*(3 + 28*x + 58*x^2 + 28*x^3 + 3*x^4)/(1-x)^8. [Colin Barker, May 08 2012]
EXAMPLE
a(2) = (2^7 - 2)/6 = 126/6 = 21.
MATHEMATICA
Table[(n^7-n)/6, {n, 0, 30}] (* or *) LinearRecurrence[ {8, -28, 56, -70, 56, -28, 8, -1}, {0, 0, 21, 364, 2730, 13020, 46655, 137256}, 30] (* Harvey P. Dale, Apr 16 2014 *)
PROG
(Magma) [(n^7-n)/6: n in [0..40]]; // Vincenzo Librandi, May 02 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Henry Bottomley, Jun 06 2005
STATUS
approved