a(1) = 1; for n > 1, a(n) = sigma((2^n)-1) - sigma((2^(n-1))-1), where sigma is A000203, the sum of divisors.

A329890

a(1) = 1; for n > 1, a(n) = sigma((2^n)-1) - sigma((2^(n-1))-1), where sigma is A000203, the sum of divisors.

Terms

    a(0) =1a(1) =3a(2) =4a(3) =16a(4) =8a(5) =72a(6) =24a(7) =304a(8) =160a(9) =944a(10) =624a(11) =6576a(12) =-544a(13) =14336a(14) =16384a(15) =72544a(16) =19616a(17) =342528a(18) =50688a(19) =1475584a(20) =466176a(21) =3443712a(22) =2657376a(23) =29486880a(24) =-3340288a(25) =54808448a(26) =65971360a(27) =306781024a(28) =77647680a(29) =1475408064

External references