a(n) = phi( 2^(2*n) + 2^n + 1 ) / (6*n), where phi() is Euler's totient function (A000010).

A376482

a(n) = phi( 2^(2*n) + 2^n + 1 ) / (6*n), where phi() is Euler's totient function (A000010).

Terms

    a(0) =1a(1) =1a(2) =4a(3) =6a(4) =30a(5) =72a(6) =336a(7) =720a(8) =4864a(9) =9900a(10) =54498a(11) =139968a(12) =728208a(13) =1820448a(14) =11748240a(15) =23224320a(16) =142888536a(17) =424189440a(18) =2066689584a(19) =4704480000a(20) =34426570752a(21) =75016279008a(22) =437072997306

External references