A209637 Matula-numbers computed for rooted trees encoded by A071162 when interpreted in once-halved bit-tuple format.

1, 2, 3, 4, 5, 7, 6, 8, 11, 17, 13, 19, 10, 14, 12, 16, 31, 59, 41, 67, 29, 43, 37, 53, 22, 34, 26, 38, 20, 28, 24, 32, 127, 277, 179, 331, 109, 191, 157, 241, 79, 139, 101, 163, 71, 107, 89, 131, 62, 118, 82, 134, 58, 86, 74, 106, 44, 68, 52, 76, 40, 56, 48

Offset

0,2

Comments

Sequence A209638 gives the same terms sorted into ascending order.

References

Mueller, Szymanski, Knop and Trinajstic, A Comparison between the Matula Numbers and Bit-tuple Notation for Rooted Trees J. Chem. Inf. Comput. Sci. 1995, 35, pp. 211--213.

Links

Table of n, a(n) for n=0..62.

Formula

a(n) = A209636(A054429(n)) = A127301(A057505(A071163(n))) = A127301(A057163(A071163(n))).

Prog

(Python)
from sympy import prime
from mpmath import log
def a054429(n): return 3*(2**int(log(n, 2))) - (n + 1)
def a209636(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
def a(n): return 1 if n==0 else a209636(a054429(n)) # Indranil Ghosh, May 26 2017

Crossrefs

Sequence in context: A066937 A217266 A347539 * A347540 A120750 A265672

Adjacent sequences: A209634 A209635 A209636 * A209638 A209639 A209640

Keyword

nonn,easy

Author

Antti Karttunen, Mar 11 2012

Status

approved