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Number of terms in the set InvPhi(8*prime(n)), where prime(n) is the n-th prime.
5

%I #17 Nov 07 2024 08:32:45

%S 6,10,9,3,6,3,2,0,4,6,0,3,4,3,0,4,0,0,3,2,3,3,4,4,3,2,0,2,0,4,3,6,2,3,

%T 2,0,0,3,0,4,6,0,4,3,0,3,0,0,0,0,4,6,0,4,0,0,2,0,3,4,0,4,3,0,0,0,0,0,

%U 2,0,0,4,0,3,0,0,0,0,2,3,4,0,6,3,0,4,2,0,0,0,0,2,3,6,3,0,6,0,0,0,0,2,0,0

%N Number of terms in the set InvPhi(8*prime(n)), where prime(n) is the n-th prime.

%H Amiram Eldar, <a href="/A071630/b071630.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..1000 from Donovan Johnson)

%H Max Alekseyev, <a href="https://oeis.org/wiki/User:Max_Alekseyev/gpscripts">PARI/GP Scripts for Miscellaneous Math Problems</a> (invphi.gp).

%e For n=5: invphi(8*11) = {89,115,178,184,230,276}, a(5) = 6.

%p [seq(nops(invphi(8*ithprime(i))),i=1..128)];

%o (PARI) a(n) = invphiNum(8*prime(n)); \\ _Amiram Eldar_, Nov 07 2024, using _Max Alekseyev_'s invphi.gp

%Y Cf. A000010, A002202, A005277, A007617, A058888, A071629-A071634.

%K nonn

%O 1,1

%A _Labos Elemer_, May 30 2002