Divide natural numbers in groups with prime(n) elements and add together.

Terms

a(0) =3a(1) =12a(2) =40a(3) =98a(4) =253a(5) =455a(6) =850a(7) =1292a(8) =2047a(9) =3335a(10) =4495a(11) =6623a(12) =8938a(13) =11180a(14) =14335a(15) =18815a(16) =24249a(17) =28731a(18) =35845a(19) =42884a(20) =49348a(21) =59408a(22) =69139a(23) =81791a(24) =98164a(25) =112211a(26) =124939a(27) =141026a(28) =155434a(29) =173681