OFFSET
0,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
FORMULA
(n+1)(n+2)(n+3)(3n^2+12n+10)/30 = 2*A024166(n+1).
G.f. 2*(1+4*x+x^2) / (x-1)^6 . - R. J. Mathar, Sep 15 2012
EXAMPLE
a(3)=(1*2)^2/2+(2*3)^2/2+(3.4)^2/2=2+18+72=92
MATHEMATICA
Table[Sum[(k(k+1))^2/2, {k, n}], {n, 40}] (* or *) LinearRecurrence[{6, -15, 20, -15, 6, -1}, {2, 20, 92, 292, 742, 1624}, 40] (* Harvey P. Dale, Oct 04 2020 *)
PROG
(PARI) for(i=1, 20, print1(", "sum(j=1, i, (j*(j+1))^2/2)))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jon Perry, Jul 31 2003
EXTENSIONS
More terms from Jason Earls, Aug 01 2003
Definition clarified by Harvey P. Dale, Oct 04 2020
STATUS
approved