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A209637 Matula-numbers computed for rooted trees encoded by A071162 when interpreted in once-halved bit-tuple format. 5
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 (list; graph; refs; listen; history; text; internal format)
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: A091995 A066937 A217266 * A120750 A265672 A178528

Adjacent sequences:  A209634 A209635 A209636 * A209638 A209639 A209640

KEYWORD

nonn,easy

AUTHOR

Antti Karttunen, Mar 11 2012

STATUS

approved

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Last modified April 17 13:31 EDT 2021. Contains 343063 sequences. (Running on oeis4.)