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 A285707 a(n) = gcd(n, A079277(n)), a(1) = 1. 4
 1, 1, 1, 2, 1, 2, 1, 4, 3, 2, 1, 3, 1, 2, 3, 8, 1, 2, 1, 4, 3, 2, 1, 6, 5, 2, 9, 4, 1, 3, 1, 16, 3, 2, 5, 4, 1, 2, 3, 8, 1, 6, 1, 4, 9, 2, 1, 12, 7, 10, 3, 4, 1, 6, 5, 7, 3, 2, 1, 6, 1, 2, 7, 32, 5, 2, 1, 4, 3, 2, 1, 8, 1, 2, 15, 4, 7, 6, 1, 16, 27, 2, 1, 3, 5, 2, 3, 8, 1, 9, 7, 4, 3, 2, 5, 3, 1, 2, 9, 20, 1, 6, 1, 8, 3, 2, 1, 12, 1, 10, 3, 14, 1, 6, 5, 4, 9 (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(n, A079277(n)) = gcd(n, A285699(n)). a(n) = n / A285708(n). MATHEMATICA Table[GCD[n, #] &@ If[n <= 2, 1, Module[{k = n - 2, e = Floor@ Log2@ n}, While[PowerMod[n, e, k] != 0, k--]; k]], {n, 117}] (* Michael De Vlieger, Apr 26 2017 *) PROG (PARI) A007947(n) = factorback(factorint(n)[, 1]); A079277(n) = { my(r); if((n > 1 && !bitand(n, (n-1))), (n/2), r=A007947(n); if(1==n, 0, k = n-1; while(A007947(k*n) <> r, k = k-1); k)); }; A285707(n) = if(1==n, n, gcd(A079277(n), n)); (Scheme) (define (A285707 n) (if (= 1 n) n (gcd n (A079277 n)))) (Python) from sympy import divisors, 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, a079277(n)) print([a(n) for n in range(1, 151)]) # Indranil Ghosh, Apr 26 2017 CROSSREFS Cf. A009195, A079277, A285699, A285708, A285711. Sequence in context: A123317 A231557 A171453 * A164879 A200219 A270120 Adjacent sequences:  A285704 A285705 A285706 * A285708 A285709 A285710 KEYWORD nonn,look,changed AUTHOR Antti Karttunen, Apr 26 2017 STATUS approved

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Last modified May 18 03:03 EDT 2021. Contains 343994 sequences. (Running on oeis4.)