A339898 - OEIS

%I #9 Dec 28 2020 09:51:38

%S 0,0,0,0,0,2,1,2,0,2,4,4,1,5,9,14,0,2,1,2,0,2,4,5,7,8,9,14,10,32,9,29,

%T 0,0,0,0,1,2,0,2,1,0,4,4,3,11,4,14,1,2,0,2,7,5,3,2,0,2,4,14,6,20,34,

%U 14,0,2,4,5,24,20,16,23,28,41,9,29,112,68,24,74,3,11,19,5,27,2,58,14,16,50,84,119,388,356

%N a(n) = A019565(2n)-1 mod A000265(phi(A019565(2n))).

%H Antti Karttunen, <a href="/A339898/b339898.txt">Table of n, a(n) for n = 0..8192</a>

%H Antti Karttunen, <a href="/A339898/a339898.txt">Data supplement: n, a(n) computed for n = 0..65537</a>

%F a(n) = A339809(2*n) modulo A339971(n), where A339971(n) = A053575(A019565(2n)).

%o (PARI)

%o A000265(n) = (n>>valuation(n,2));

%o A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };

%o A339898(n) = { my(x=A019565(2*n)); ((x-1)%A000265(eulerphi(x))); };

%Y Cf. A053575, A019565, A339809, A339821, A339971, A339899, A339901.

%Y Cf. A339973 (positions of zeros).

%K nonn

%O 0,6

%A _Antti Karttunen_, Dec 28 2020