a(n) = floor ( (2nd elementary symmetric function of 2,3,...,n+2)/(2+3+...+n+2) ).

Terms

a(0) =1a(1) =2a(2) =5a(3) =7a(4) =10a(5) =14a(6) =18a(7) =23a(8) =28a(9) =34a(10) =40a(11) =47a(12) =54a(13) =61a(14) =70a(15) =78a(16) =87a(17) =97a(18) =107a(19) =118a(20) =129a(21) =141a(22) =153a(23) =166a(24) =179a(25) =192a(26) =207a(27) =221a(28) =236a(29) =252