[seqfan] Re: Nonmembers of Range of Euler Phi Function
T. D. Noe
noe at sspectra.com
Sun Sep 19 20:16:04 CEST 2010
At 12:47 PM -0500 9/19/10, Ray Chandler wrote:
>> I want to submit a sequence whose nth term is, if it exists,
>> the smallest positive integral multiple of 2^n not in the
>> range of the Euler phi function.
>> I know the terms up to n=5 (so the offset is n=0): 3, 14, 68,
>> 152, 304, 608
>>
>
>Using Tony Noe's b-file from A005277, sequence continues
>3, 14, 68, 152, 304, 608, 1984, 3968, 12032, 24064, ...
Calculating up to n=17, I find that these numbers all have the form 2^n *
p, where p is 3, 7, 23, 31, 47. It's not clear what sequence p is. Might
be A122094, Prime divisors of Mersenne numbers. Primes p such that the
multiplicative order of 2 modulo p is prime, in which case the next prime
is 89.
Tony
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