A325375 a(n) = gcd(A325319(n), A325320(n)).

3, 1, 9, 1, 3, 1, 1, 3, 3, 1, 9, 1, 1, 7, 1, 5, 9, 1, 1, 1, 3, 1, 1, 3, 1, 1, 3, 1, 3, 9, 1, 1, 1, 1, 3, 1, 1, 1, 9, 1, 1, 1, 7, 1, 1, 9, 1, 3, 5, 3, 3, 9, 1, 1, 1, 3, 1, 3, 1, 5, 1, 1, 3, 1, 1, 1, 1, 1, 1, 3, 3, 1, 1, 3, 1, 1, 1, 3, 3, 1, 25, 1, 1, 9, 1, 1, 9, 1, 3, 1, 27, 1, 1, 1, 1, 3, 9, 1, 49, 1, 1, 1, 1, 1, 1

Offset: 1

Author

Antti Karttunen, Apr 22 2019

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..25000

Crossrefs

Cf. A228058, A325319, A325320, A325376.

Programs

PARI

up_to = 25000;
isA228058(n) = if(!(n%2)||(omega(n)<2),0,my(f=factor(n),y=0); for(i=1,#f~,if(1==(f[i,2]%4), if((1==y)||(1!=(f[i,1]%4)),return(0),y=1), if(f[i,2]%2, return(0)))); (y));
A228058list(up_to) = { my(v=vector(up_to), k=0, n=0); while(kA228058(n), k++; v[k] = n)); (v); };
v228058 = A228058list(up_to);
A228058(n) = v228058[n];
A048250(n) = factorback(apply(p -> p+1,factor(n)[,1]));
A325313(n) = (A048250(n) - n);
A162296(n) = sumdiv(n, d, d*(1-issquarefree(d)));
A325314(n) = (n - A162296(n));
A325319(n) = -A325313(A228058(n));
A325320(n) = -A325314(A228058(n));
A325375(n) = gcd(A325319(n),A325320(n));

Formula

a(n) = gcd(A325319(n), A325320(n)).