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A379478
a(n) = 1 if the greatest common divisor of n, sigma(n) and A003961(n) is 1 and gcd(A003961(n)-2n, A003961(n)-sigma(n)) > 1, otherwise 0.
0
0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
OFFSET
1
FORMULA
a(n) = A379476(n) - A379475(n).
PROG
(PARI)
A003961(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); };
A372565(n) = gcd([n, sigma(n), A003961(n)]);
A326057(n) = { my(u=A003961(n)); gcd(u-(2*n), u-sigma(n)); };
A379478(n) = ((1==A372565(n)) && (A326057(n)>1));
CROSSREFS
Characteristic function of A379479.
Sequence in context: A079365 A037822 A144600 * A011686 A275305 A169671
KEYWORD
nonn,new
AUTHOR
Antti Karttunen, Dec 23 2024
STATUS
approved