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A209638 Sequence A209636 (or A209637) sorted into ascending order. 5
1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 16, 17, 19, 20, 22, 24, 26, 28, 29, 31, 32, 34, 37, 38, 40, 41, 43, 44, 48, 52, 53, 56, 58, 59, 62, 64, 67, 68, 71, 74, 76, 79, 80, 82, 86, 88, 89, 96, 101, 104, 106, 107, 109, 112, 116, 118, 124, 127, 128, 131, 134 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

These are Matula-numbers (see A061773) for the rooted trees where no vertices with more than one non-leaf branch ever occur. In other words, natural numbers which are either some power of 2, or of the form 2^k * p_i, where k >= 0, and p_i is the i-th prime (A000040(i)), with i being one of the terms of this sequence.

LINKS

Table of n, a(n) for n=0..63.

Index entries for sequences related to Matula-Goebel numbers

PROG

(Python)

from sympy import prime

def a(n):

    n = 2*n

    m = 1

    if n<2: return 1

    while n>1:

        if n%2==0:

            n/=2

            m*=2

        else:

            n=(n - 1)/2

            m=prime(m)

    return m

print sorted([a(n) for n in xrange(101)]) # Indranil Ghosh, May 26 2017

CROSSREFS

Sorted version of A209636 and A209637.

Subset of A093641 and A122132.

Sequence in context: A162722 A123345 A093641 * A191844 A096157 A066522

Adjacent sequences:  A209635 A209636 A209637 * A209639 A209640 A209641

KEYWORD

nonn

AUTHOR

Antti Karttunen, Mar 11 2012

STATUS

approved

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Last modified January 21 11:47 EST 2019. Contains 319354 sequences. (Running on oeis4.)