Divide odd numbers into groups with prime(n) elements and add together.

Terms

a(0) =4a(1) =21a(2) =75a(3) =189a(4) =495a(5) =897a(6) =1683a(7) =2565a(8) =4071a(9) =6641a(10) =8959a(11) =13209a(12) =17835a(13) =22317a(14) =28623a(15) =37577a(16) =48439a(17) =57401a(18) =71623a(19) =85697a(20) =98623a(21) =118737a(22) =138195a(23) =163493a(24) =196231a(25) =224321a(26) =249775a(27) =281945a(28) =310759a(29) =347249