OFFSET
0,7
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (2,-1,0,0,0,0,1,-2,1).
FORMULA
From R. J. Mathar, Apr 15 2010: (Start)
a(n) = 2*a(n-1) - a(n-2) + a(n-7) - 2*a(n-8) + a(n-9).
G.f.: x^5 / ((1-x)^3*(x^6+x^5+x^4+x^3+x^2+x+1) ). (End)
MATHEMATICA
Table[Floor[n(n - 1)/14], {n, 0, 59}] (* Alonso del Arte, Aug 26 2011 *)
LinearRecurrence[{2, -1, 0, 0, 0, 0, 1, -2, 1}, {0, 0, 0, 0, 0, 1, 2, 3, 4}, 70] (* Harvey P. Dale, Oct 22 2016 *)
PROG
(Magma) [Floor(n*(n-1)/14): n in [0..70]]; // Vincenzo Librandi, Aug 29 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved