a(n) = phi(sigma(n)) * A064989(sigma(n)), where A064989 shifts the prime factorization one step towards lower primes.

A353750

a(n) = phi(sigma(n)) * A064989(sigma(n)), where A064989 shifts the prime factorization one step towards lower primes.

Terms

    a(0) =1a(1) =4a(2) =2a(3) =30a(4) =4a(5) =8a(6) =4a(7) =48a(8) =132a(9) =24a(10) =8a(11) =60a(12) =30a(13) =16a(14) =16a(15) =870a(16) =24a(17) =528a(18) =24a(19) =120a(20) =16a(21) =48a(22) =16a(23) =96a(24) =870a(25) =120a(26) =48a(27) =120a(28) =48a(29) =96

External references