2nd elementary symmetric function of first n+1 positive integers congruent to 1 mod 3.

Terms

a(0) =4a(1) =39a(2) =159a(3) =445a(4) =1005a(5) =1974a(6) =3514a(7) =5814a(8) =9090a(9) =13585a(10) =19569a(11) =27339a(12) =37219a(13) =49560a(14) =64740a(15) =83164a(16) =105264a(17) =131499a(18) =162355a(19) =198345a(20) =240009a(21) =287914a(22) =342654a(23) =404850a(24) =475150a(25) =554229a(26) =642789a(27) =741559a(28) =851295a(29) =972780