OFFSET
1,2
COMMENTS
Since phi(p) = p - 1, allowing prime numbers in this sequence would make it A006005, the primes with a 1 replacing the initial 2.
Number of terms < 10^k, k=1,2,3,...: 4, 13, 61, 310, 1628, 9029, 51207, 295132, ..., . Robert G. Wilson v, Feb 19 2019
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 8 because phi(8) = 4, which is greater than phi(4) = phi(6) = 2. (phi(5) = 4 and phi(7) = 6 are ignored because 5 and 7 are prime).
MATHEMATICA
htcList = {1}; i = 4; currMax = 1; searchMax = 1000; While[i < searchMax, If[Not[PrimeQ[i]] && EulerPhi[i] > currMax, htcList = {htcList, i}; currMax = EulerPhi[i]]; i++ ]; Flatten[htcList]
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Alonso del Arte, Oct 20 2007
STATUS
approved