OFFSET
1,1
FORMULA
a(n) = (k+1)(k+2)...(k+n) + nk + n(n+1)/2, k = n(n-1)/2
MAPLE
seq(product(i, i=n*(n-1)/2+1..n*(n-1)/2+n)+n*(n+1)/2+n*(n-1)/2*n, n=1..20);
MATHEMATICA
nx[n_]:=Module[{trn=(n(n+1))/2, r}, r=Range[trn-n+1, trn]; Total[r]+ Times@@r]; Array[nx, 20] (* Harvey P. Dale, Jan 03 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Nov 09 2002
EXTENSIONS
More terms from Sascha Kurz, Jan 12 2003
STATUS
approved