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A340087
a(n) = gcd(n-1, A091732(n)), where A091732 is an infinitary analog of Euler's phi function.
5
1, 1, 2, 3, 4, 1, 6, 1, 8, 1, 10, 1, 12, 1, 2, 15, 16, 1, 18, 1, 4, 1, 22, 1, 24, 1, 2, 9, 28, 1, 30, 1, 4, 1, 2, 1, 36, 1, 2, 3, 40, 1, 42, 1, 4, 1, 46, 1, 48, 1, 2, 3, 52, 1, 2, 1, 4, 1, 58, 1, 60, 1, 2, 9, 16, 5, 66, 1, 4, 3, 70, 1, 72, 1, 2, 3, 4, 1, 78, 1, 80, 1, 82, 1, 4, 1, 2, 3, 88, 1, 18, 1, 4, 1, 2, 5, 96
OFFSET
1,3
LINKS
FORMULA
a(n) = gcd(n-1, A091732(n)).
a(n) = A091732(n) / A340088(n).
For n > 1, a(n) = (n-1) / A340089(n).
PROG
(PARI)
ispow2(n) = (n && !bitand(n, n-1));
A302777(n) = ispow2(isprimepower(n));
A091732(n) = { my(m=1); while(n > 1, fordiv(n, d, if((d<n)&&A302777(n/d), m *= ((n/d)-1); n = d; break))); (m); };
A340087(n) = gcd(n-1, A091732(n));
CROSSREFS
Cf. also A049559.
Sequence in context: A050144 A124406 A225650 * A239223 A143771 A364255
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 31 2020
STATUS
approved