[ (n+1)/(n-1) ] + [ (n+2)/(n-2) ] + ... + [ (2n-1)/1 ].

Terms

a(0) =3a(1) =7a(2) =11a(3) =16a(4) =22a(5) =26a(6) =33a(7) =39a(8) =45a(9) =51a(10) =59a(11) =64a(12) =72a(13) =80a(14) =86a(15) =92a(16) =103a(17) =107a(18) =117a(19) =125a(20) =131a(21) =139a(22) =149a(23) =156a(24) =164a(25) =172a(26) =182a(27) =188a(28) =200a(29) =204