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A330749
a(n) = gcd(n, A064989(n)), where A064989 is fully multiplicative with a(2) = 1 and a(prime(k)) = prime(k-1) for odd primes.
9
1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 6, 1, 1, 1, 1, 5, 4, 1, 1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 6, 1, 1, 1, 1, 1, 2, 1, 1, 1, 5, 1, 4, 1, 1, 3, 1, 7, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 6, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 15
OFFSET
1,6
LINKS
FORMULA
a(n) = gcd(n, A064989(n)).
a(n) = n / A319626(n).
a(n) = A064989(A322361(n)).
PROG
(PARI) A330749(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); gcd(n, factorback(f)); };
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 29 2019
STATUS
approved