login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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(list(filter(lambda i: core(i) == i, divisors(n))))

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 xrange(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

AUTHOR

Antti Karttunen, Apr 26 2017

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 20 02:08 EDT 2019. Contains 328244 sequences. (Running on oeis4.)