(prime(n)*(prime(n+1)-1) + (prime(n)-1)*prime(n+1)) / 2.

Terms

a(0) =11a(1) =29a(2) =68a(3) =131a(4) =206a(5) =305a(6) =416a(7) =641a(8) =869a(9) =1113a(10) =1478a(11) =1721a(12) =1976a(13) =2441a(14) =3071a(15) =3539a(16) =4023a(17) =4688a(18) =5111a(19) =5691a(20) =6476a(21) =7301a(22) =8540a(23) =9698a(24) =10301a(25) =10916a(26) =11555a(27) =12206a(28) =14231a(29) =16508