a(n) = 2*sigma(n) - A003961(n), where sigma is the sum of divisors function and A003961 is fully multiplicative function with a(prime(i)) = prime(i+1).

A377984

a(n) = 2*sigma(n) - A003961(n), where sigma is the sum of divisors function and A003961 is fully multiplicative function with a(prime(i)) = prime(i+1).

Terms

    a(0) =1a(1) =3a(2) =3a(3) =5a(4) =5a(5) =9a(6) =5a(7) =3a(8) =1a(9) =15a(10) =11a(11) =11a(12) =11a(13) =15a(14) =13a(15) =-19a(16) =17a(17) =3a(18) =17a(19) =21a(20) =9a(21) =33a(22) =19a(23) =-15a(24) =13a(25) =33a(26) =-45a(27) =13a(28) =29a(29) =39

External references