a(n) = [ 2nd elementary symmetric function of {sqrt(k+1)} ], k = 1,2,...,n.

Terms

a(0) =2a(1) =8a(2) =20a(3) =38a(4) =64a(5) =99a(6) =145a(7) =203a(8) =274a(9) =360a(10) =462a(11) =581a(12) =719a(13) =877a(14) =1056a(15) =1258a(16) =1484a(17) =1735a(18) =2013a(19) =2319a(20) =2655a(21) =3021a(22) =3419a(23) =3850a(24) =4317a(25) =4819a(26) =5359a(27) =5937a(28) =6556a(29) =7216