A209638 Sequence A209636 (or A209637) sorted into ascending order.

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

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 range(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