A285736 - OEIS

%I #13 May 09 2021 09:51:11

%S 1,0,1,0,1,0,3,2,3,0,1,0,1,0,5,4,3,4,7,0,1,0,3,2,3,0,1,0,1,0,3,2,5,0,

%T 7,2,7,0,5,2,3,0,1,0,1,0,5,4,3,8,7,0,7,8,3,4,5,0,1,0,1,0,3,2,3,0,1,0,

%U 1,0,3,2,3,0,1,0,1,0,3,2,3,0,1,0,1,0,5,4,3,4,15,0,1,0,11,10,5,4,7,6,9,0,11,2,11,0,15,2,7,0,5,2,3,0,1,0,1,0,3

%N a(n) = A285735(n) - A285734(n) = n - 2*A285734(n).

%H Antti Karttunen, <a href="/A285736/b285736.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A285735(n) - A285734(n) = n - 2*A285734(n).

%o (Scheme)

%o (define (A285736 n) (- (A285735 n) (A285734 n)))

%o (define (A285736 n) (- n (* 2 (A285734 n))))

%o (Python)

%o from sympy.ntheory.factor_ import core

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

%o def a285734(n):

%o     if n==1: return 0

%o     j=n//2

%o     while True:

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

%o         else: j-=1

%o def a285736(n): return n - 2*a285734(n)

%o print([a285736(n) for n in range(1, 101)]) # _Indranil Ghosh_, May 02 2017

%Y Cf. A005117 (2*A005117 gives the positions of zeros), A285734, A285735.

%K nonn

%O 1,7

%A _Antti Karttunen_, May 02 2017