a(n)= Sum_{d divides n} a(abs(n/d-d)).

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =18a(6) =38a(7) =76a(8) =156a(9) =313a(10) =634a(11) =1268a(12) =2556a(13) =5112a(14) =10260a(15) =20524a(16) =41125a(17) =82250a(18) =164660a(19) =329320a(20) =658954a(21) =1317926a(22) =2636478a(23) =5272956a(24) =10547220a(25) =21094441a(26) =42191418a(27) =84382912a(28) =168770944a(29) =337541888