An approximation to sigma_{5/2}(n): ceiling( sum_{d|n} d^(5/2) ).

Terms

a(0) =1a(1) =7a(2) =17a(3) =39a(4) =57a(5) =111a(6) =131a(7) =220a(8) =260a(9) =379a(10) =403a(11) =642a(12) =611a(13) =870a(14) =944a(15) =1244a(16) =1193a(17) =1729a(18) =1575a(19) =2200a(20) =2168a(21) =2679a(22) =2538a(23) =3645a(24) =3182a(25) =4063a(26) =4048a(27) =5051a(28) =4530a(29) =6284