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 A285711 a(n) = gcd(A051953(n), A079277(n)), a(1) = 1. 5
 1, 1, 1, 2, 1, 4, 1, 4, 3, 2, 1, 1, 1, 8, 1, 8, 1, 4, 1, 4, 9, 4, 1, 2, 5, 2, 9, 16, 1, 1, 1, 16, 1, 2, 1, 8, 1, 4, 3, 8, 1, 6, 1, 8, 3, 8, 1, 4, 7, 10, 1, 4, 1, 12, 5, 1, 3, 2, 1, 2, 1, 32, 1, 32, 1, 2, 1, 4, 1, 2, 1, 16, 1, 2, 5, 8, 1, 18, 1, 16, 27, 2, 1, 3, 1, 4, 1, 16, 1, 3, 1, 16, 3, 16, 1, 1, 1, 8, 3, 20, 1, 2, 1, 8, 3, 2, 1, 24, 1, 10, 3, 2, 1, 6, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS Antti Karttunen, Table of n, a(n) for n = 1..10000 FORMULA a(1) = 1; for n > 1, a(n) = gcd(A051953(n), A079277(n)). MATHEMATICA Table[GCD[n - EulerPhi@ n, If[n <= 2, 1, Module[{k = n - 2, e = Floor@ Log2@ n}, While[PowerMod[n, e, k] != 0, k--]; k]]], {n, 115}] (* Michael De Vlieger, Apr 26 2017 *) PROG (Scheme) (define (A285711 n) (if (= 1 n) n (gcd (A051953 n) (A079277 n)))) (Python) from sympy import divisors, totient, gcd from sympy.ntheory.factor_ import core def a007947(n): return max(i for i in divisors(n) if core(i) == i) def a079277(n):     k=n - 1     while True:         if a007947(k*n) == a007947(n): return k         else: k-=1 def a(n): return 1 if n==1 else gcd(n - totient(n), a079277(n)) print([a(n) for n in range(1, 151)]) # Indranil Ghosh, Apr 26 2017 CROSSREFS Cf. A009195, A051953, A079277, A285707, A285709, A285710. Sequence in context: A322968 A072721 A339792 * A035092 A160598 A107457 Adjacent sequences:  A285708 A285709 A285710 * A285712 A285713 A285714 KEYWORD nonn AUTHOR Antti Karttunen, Apr 26 2017 STATUS approved

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Last modified May 17 12:55 EDT 2021. Contains 343971 sequences. (Running on oeis4.)