A077544 - OEIS

%I #8 Dec 05 2013 19:55:53

%S 2,11,135,5074,360425,39070191,5967561775,1220096909060,

%T 321570878429169,106137499051584505,42873948150095463071,

%U 20803502274492921984870,11938961126118491232769105,7998487694738166709923841379

%N Product of next n numbers + sum of next n numbers.

%F a(n) = (k+1)(k+2)...(k+n) + nk + n(n+1)/2, k = n(n-1)/2

%p 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);

%t 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 *)

%K nonn

%O 1,1

%A _Amarnath Murthy_, Nov 09 2002

%E More terms from _Sascha Kurz_, Jan 12 2003