OFFSET
1,1
COMMENTS
This is a quadratic sequence.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Wolfram Alpha, Table of floor(7n^2/2) + floor(5n/2) + floor(3n/7).
Index entries for linear recurrences with constant coefficients, signature (1,1,-1,0,0,0,1,-1,-1,1).
FORMULA
a(n) = (n(7n + 5) + (-1)^n - 1)/2 + A132270(3n + 1). [Bruno Berselli, Mar 28 2014]
a(n) = +a(n-1) +a(n-2) -a(n-3) +a(n-7) -a(n-8) -a(n-9) +a(n-10). [Bruno Berselli, Mar 28 2014]
EXAMPLE
For n=3, a(3) = floor(7*3^2/2) + floor(5*3/2) + floor(3*3/7) = 39.
MAPLE
A239831:=n->floor(7*n^2/2) + floor(5*n/2) + floor(3*n/7); seq(A239831(n), n=1..50); # Wesley Ivan Hurt, Mar 28 2014
MATHEMATICA
Table[Floor[7 n^2/2] + Floor[5 n/2] + Floor[3 n/7], {n, 50}] (* Bruno Berselli, Mar 28 2014 *)
PROG
(Magma) [Floor(7*n^2/2) + Floor(5*n/2) + Floor(3*n/7): n in [1..50]]; // Vincenzo Librandi, Mar 29 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Katherine Guo, Mar 27 2014
EXTENSIONS
More terms from Bruno Berselli, Mar 28 2014
STATUS
approved