A227533 Smallest e > 1 such that (2n)^e is a totient, or 0 if no such e exists.
2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 4, 2, 3, 2, 2, 2, 4, 2, 2, 2, 2, 2, 3, 2, 5, 2, 2, 2, 2, 2, 2, 3, 3, 2, 4, 2, 15, 2, 2, 4, 2, 2, 3, 2, 3, 2, 4, 2, 2, 2, 2, 2, 3, 2, 7, 2, 2, 2, 2, 2, 2, 2, 4, 2, 3, 2, 2, 2, 2, 3, 3, 2, 8, 2, 2, 4, 15, 2, 2, 3, 2, 2, 5, 2, 4, 2, 2
Offset: 1
Keywords
Examples
a(1) = 2 because phi(5) = 2^2. a(11) = 3 because phi(13315) = 22^3 but phi(k) is not equal to 22^2 for any k.
Links
- Charles R Greathouse IV, Table of n, a(n) for n = 1..100000
- Charles R Greathouse IV, GP script for efficiently computing the sequence
Programs
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PARI
a(n)=my(k=2);while(!istotient((2*n)^k),k++);k
Comments