a(n) = 2*sigma(n) - sigma(A003961(n)), where A003961 is fully multiplicative with a(prime(i)) = prime(i+1).
A378752
a(n) = 2*sigma(n) - sigma(A003961(n)), where A003961 is fully multiplicative with a(prime(i)) = prime(i+1).
Terms
- a(0) =1a(1) =2a(2) =2a(3) =1a(4) =4a(5) =0a(6) =4a(7) =-10a(8) =-5a(9) =4a(10) =10a(11) =-22a(12) =10a(13) =0a(14) =0a(15) =-59a(16) =16a(17) =-46a(18) =16a(19) =-20a(20) =-8a(21) =16a(22) =18a(23) =-120a(24) =5a(25) =12a(26) =-76a(27) =-44a(28) =28a(29) =-48
External references
- oeis: A378752