a(n) = sum of the numbers between the two n's in A026342.

Terms

a(0) =0a(1) =3a(2) =2a(3) =18a(4) =17a(5) =24a(6) =23a(7) =55a(8) =83a(9) =98a(10) =97a(11) =113a(12) =141a(13) =140a(14) =159a(15) =192a(16) =242a(17) =282a(18) =309a(19) =371a(20) =420a(21) =453a(22) =507a(23) =506a(24) =542a(25) =601a(26) =600a(27) =662a(28) =727a(29) =770