A077544 Product of next n numbers + sum of next n numbers.

2, 11, 135, 5074, 360425, 39070191, 5967561775, 1220096909060, 321570878429169, 106137499051584505, 42873948150095463071, 20803502274492921984870, 11938961126118491232769105, 7998487694738166709923841379

Offset

1,1

Links

Table of n, a(n) for n=1..14.

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

Sequence in context: A041725 A330638 A296571 * A087480 A060059 A365357

Adjacent sequences: A077541 A077542 A077543 * A077545 A077546 A077547

Keyword

nonn

Author

Amarnath Murthy, Nov 09 2002

Extensions

More terms from Sascha Kurz, Jan 12 2003

Status

approved