



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
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OFFSET

0,2


COMMENTS

These are Matulanumbers (see A061773) for the rooted trees where no vertices with more than one nonleaf 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 ith 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 MatulaGoebel 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,changed


AUTHOR

Antti Karttunen, Mar 11 2012


STATUS

approved



