Define F(n) = 2^(2^n)+1 = the n-th Fermat number, M(n) = 2^n-1 = the n-th Mersenne number. Then a(n) = F(n)+M(n)+1=2^(2^n)+1+2^n-1+1 = 2^(2^n)+2^n+1 = F(n)+2^n.
A119561
Define F(n) = 2^(2^n)+1 = the n-th Fermat number, M(n) = 2^n-1 = the n-th Mersenne number. Then a(n) = F(n)+M(n)+1=2^(2^n)+1+2^n-1+1 = 2^(2^n)+2^n+1 = F(n)+2^n.
Terms
- a(0) =4a(1) =7a(2) =21a(3) =265a(4) =65553a(5) =4294967329
External references
- oeis: A119561