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A286107 a(1) = 0, for n > 1, if A286106(n) > 0, then a(n) = A285735(n), otherwise a(n) = A285734(n). 6
0, 1, 2, 2, 3, 3, 5, 5, 6, 5, 5, 6, 7, 7, 10, 10, 7, 7, 13, 10, 10, 11, 13, 13, 14, 13, 13, 14, 14, 15, 14, 15, 19, 17, 14, 19, 15, 19, 17, 19, 19, 21, 21, 22, 23, 23, 26, 26, 23, 29, 29, 26, 23, 23, 26, 26, 26, 29, 29, 30, 30, 31, 33, 33, 31, 33, 33, 34, 34, 35, 34, 35, 38, 37, 38, 38, 38, 39, 38, 41, 39, 41, 41, 42, 42, 43, 41, 46, 46, 47, 38, 46, 46, 47 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

After the initial zero, all terms are squarefree numbers (A005117).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

If A286105(A285735(n)) > A286105(A285734(n)), a(n) = A285735(n), otherwise a(n) = A285734(n), a(1) = 0.

PROG

(Scheme) (define (A286107 n) (cond ((= 1 n) 0) ((> (A286106 n) 0) (A285735 n)) (else (A285734 n))))

(Python)

from sympy.ntheory.factor_ import core

def issquarefree(n): return core(n) == n

def a285734(n):

    if n==1: return 0

    j=int(n/2)

    while True:

        if issquarefree(j) and issquarefree(n - j): return j

        else: j-=1

def a285735(n): return n - a285734(n)

def a286105(n): return 0 if n==1 else 1 + max(a286105(a285734(n)), a286105(a285735(n)))

def a286106(n): return 0 if n==1 else a286105(a285735(n)) - a286105(a285734(n))

def a286107(n): return 0 if n==1 else a285735(n) if a286106(n)>0 else a285734(n)

print [a286107(n) for n in xrange(1, 121)] # Indranil Ghosh, May 02 2017

CROSSREFS

Cf. A005117, A285734, A285735, A286104, A286105, A286106.

Sequence in context: A169682 A082524 A099961 * A285735 A038810 A178503

Adjacent sequences:  A286104 A286105 A286106 * A286108 A286109 A286110

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 02 2017

STATUS

approved

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Last modified April 20 17:54 EDT 2019. Contains 322310 sequences. (Running on oeis4.)