Grand factorial

A(1) = 1

A(2) = 2^2 + 1^2 = 5

A(3) = 3^3 * 2^3 * 1^3 = 216

A(4) = (4^4)^(3^4)^(2^4)^(1^4) = 256^81^16

A(5) = (5^5)^^(4^5)^^(3^5)^^(2^5)^^(1^5)

etc.