A380465 - OEIS

%I #8 Jan 27 2025 11:33:56

%S -1,-1,-1,-1,-1,-1,-1,0,-1,-1,-1,-1,-1,-1,-1,0,-1,-1,-1,-1,-1,-1,-1,

%T -1,-1,-1,0,-1,-1,-1,-1,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,

%U -1,0,-1,-1,-1,-1,-1,0,-1,-1,-1,-1,-1,-1,-1,-1,-1,0,-1,-1,-1,-1,-1,-1,-1,0,-1,-1,-1,-1,-1,-1,-1,-1,0

%N Second coefficient of the lindep transform of A007947, squarefree kernel of n.

%C See A339791 for a definition of lindep-transform.

%C A059172 does not give the positions of 0's in this sequence, because this is not equal to A380439(n)-1. See comments in the latter.

%H Antti Karttunen, <a href="/A380465/b380465.txt">Table of n, a(n) for n = 1..65537</a>

%o (PARI)

%o A007947(n) = factorback(factorint(n)[, 1]); \\ From A007947

%o A380465(n) = { my(v=lindep([A007947(n), n, 1])); (v*sign(v[1]))[2]; };

%Y Cf. A007947, A380464, A380466.

%Y Cf. also A339791, A380545.

%Y Differs from A380439(n)-1 for the first time at n=261120.

%K sign

%O 1

%A _Antti Karttunen_, Jan 27 2025