a(n) = (2*cos(Pi/15))^(-n) + (2*cos(7*Pi/15))^(-n) + (2*cos(11*Pi/15))^(-n) + (2*cos(13*Pi/15))^(-n), for n >= 1.

A306610

a(n) = (2*cos(Pi/15))^(-n) + (2*cos(7*Pi/15))^(-n) + (2*cos(11*Pi/15))^(-n) + (2*cos(13*Pi/15))^(-n), for n >= 1.

Terms

    a(0) =4a(1) =24a(2) =109a(3) =524a(4) =2504a(5) =11979a(6) =57299a(7) =274084a(8) =1311049a(9) =6271254a(10) =29997829a(11) =143491199a(12) =686373809a(13) =3283190949a(14) =15704770004a(15) =75121978804a(16) =359337430474

External references