a(n) = sum of the numbers between the two n's in A026350.

Terms

a(0) =0a(1) =4a(2) =8a(3) =17a(4) =29a(5) =38a(6) =55a(7) =67a(8) =89a(9) =114a(10) =131a(11) =161a(12) =194a(13) =216a(14) =254a(15) =279a(16) =322a(17) =368a(18) =398a(19) =449a(20) =482a(21) =538a(22) =597a(23) =635a(24) =699a(25) =766a(26) =809a(27) =881a(28) =927a(29) =1004