a(n) = sum of the numbers between the two n's in A026276.

Terms

a(0) =5a(1) =8a(2) =12a(3) =23a(4) =37a(5) =54a(6) =65a(7) =87a(8) =101a(9) =128a(10) =145a(11) =177a(12) =212a(13) =234a(14) =274a(15) =317a(16) =344a(17) =392a(18) =443a(19) =475a(20) =531a(21) =566a(22) =627a(23) =691a(24) =731a(25) =800a(26) =843a(27) =917a(28) =994a(29) =1042