Problimes (first definition).

Terms

a(0) =2a(1) =4a(2) =6a(3) =9a(4) =12a(5) =15a(6) =19a(7) =23a(8) =27a(9) =31a(10) =35a(11) =40a(12) =45a(13) =50a(14) =55a(15) =60a(16) =65a(17) =70a(18) =75a(19) =80a(20) =86a(21) =92a(22) =98a(23) =104a(24) =110a(25) =116a(26) =122a(27) =128a(28) =134a(29) =140