[ n/1 ] - [ (n-1)/2 ] + [ (n-2)/3 ] - ... + ((-1)^n)[ 2/(n-1) ].

Terms

a(0) =2a(1) =2a(2) =3a(3) =4a(4) =5a(5) =4a(6) =6a(7) =7a(8) =8a(9) =7a(10) =8a(11) =9a(12) =12a(13) =10a(14) =11a(15) =12a(16) =13a(17) =12a(18) =15a(19) =16a(20) =17a(21) =14a(22) =16a(23) =17a(24) =20a(25) =19a(26) =20a(27) =21a(28) =22a(29) =19