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A328147 a(n) = A025586(n)/4 for n>=3. 1
4, 1, 4, 4, 13, 2, 13, 4, 13, 4, 10, 13, 40, 4, 13, 13, 22, 5, 16, 13, 40, 6, 22, 10, 2308, 13, 22, 40, 2308, 8, 25, 13, 40, 13, 28, 22, 76, 10, 2308, 16, 49, 13, 34, 40, 2308, 12, 37, 22, 58, 13, 40, 2308, 2308, 14, 49, 22, 76, 40, 46, 2308, 2308, 16, 49, 25, 76, 17, 52, 40, 2308, 18, 2308, 28, 85, 22, 58, 76, 202, 20, 61, 2308, 2308, 21, 64, 49, 148, 22, 76, 34, 2308, 40, 70, 2308, 2308, 24, 2308, 37, 112 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

This sequence factors out the 4 that all of the terms of A025586 for n>2 are divisible by.

LINKS

Table of n, a(n) for n=3..99.

EXAMPLE

For n=3, the Collatz sequence is 3,10,5,16,8,4,2,1. The largest term is 16, so a(3) = 16/4 = 4.

PROG

(Python)

def a(n):

    if n<3: return 0

    l=[n, ]

    while True:

        if n%2==0: n/=2

        else: n = 3*n + 1

        if not n in l:

            l+=[n, ]

            if n<2: break

        else: break

    return max(l)/4

CROSSREFS

Cf. A025586.

Sequence in context: A204714 A341100 A347264 * A151783 A258853 A275791

Adjacent sequences:  A328144 A328145 A328146 * A328148 A328149 A328150

KEYWORD

nonn

AUTHOR

P. Michael Hutchins, Oct 22 2019

EXTENSIONS

a(1)-a(2) removed from data by Michel Marcus, Nov 02 2020

STATUS

approved

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Last modified October 21 23:34 EDT 2021. Contains 348160 sequences. (Running on oeis4.)