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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A286104 If A286103(A285734(n)) < A286103(A285735(n)), a(n) = A285734(n), otherwise a(n) = A285735(n), a(1) = 0. 4
0, 1, 1, 2, 3, 3, 2, 3, 3, 5, 6, 6, 7, 7, 5, 6, 7, 7, 6, 10, 11, 11, 13, 13, 14, 13, 14, 14, 15, 15, 17, 17, 19, 17, 14, 19, 15, 19, 17, 19, 19, 21, 22, 22, 23, 23, 26, 26, 26, 29, 29, 26, 30, 31, 29, 30, 31, 29, 30, 30, 31, 31, 33, 33, 34, 33, 34, 34, 35, 35, 37, 37, 38, 37, 38, 38, 39, 39, 41, 41, 39, 41, 41, 42, 43, 43, 41, 46, 46, 47, 38, 46, 47, 47, 53, 53 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

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

LINKS

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

FORMULA

a(1) = 0, and for n > 1, if A286103(A285734(n)) < A286103(A285735(n)), a(n) = A285734(n), otherwise a(n) = A285735(n).

PROG

(Scheme) (define (A286104 n) (cond ((= 1 n) 0) ((< (A286103 (A285734 n)) (A286103 (A285735 n))) (A285734 n)) (else (A285735 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 a286103(n): return 0 if n==1 else 1 + min(a286103(a285734(n)), a286103(a285735(n)))

def a286104(n): return 0 if n==1 else  a285734(n) if a286103(a285734(n)) < a286103(a285735(n)) else a285735(n)

print [a286104(n) for n in xrange(1, 121)] # Indranil Ghosh, May 02 2017

CROSSREFS

Cf. A005117, A285734, A285735, A286103, A286107.

Sequence in context: A110006 A289831 A296611 * A137779 A191246 A248222

Adjacent sequences:  A286101 A286102 A286103 * A286105 A286106 A286107

KEYWORD

nonn

AUTHOR

Antti Karttunen, May 02 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 May 20 20:16 EDT 2019. Contains 323426 sequences. (Running on oeis4.)