a(n) is the first (and maximal) power of 2 arising during iterations of the Euler phi function with initial value n!.

A053047

a(n) is the first (and maximal) power of 2 arising during iterations of the Euler phi function with initial value n!.

Terms

    a(0) =1a(1) =2a(2) =2a(3) =8a(4) =32a(5) =64a(6) =128a(7) =1024a(8) =1024a(9) =8192a(10) =65536a(11) =262144a(12) =1048576a(13) =4194304a(14) =16777216a(15) =268435456a(16) =4294967296a(17) =8589934592a(18) =17179869184a(19) =274877906944a(20) =549755813888

External references