

A196063


The NarumiKatayama index of the rooted tree with MatulaGoebel number n.


2



0, 1, 2, 2, 4, 4, 3, 3, 8, 8, 8, 6, 6, 6, 16, 4, 6, 12, 4, 12, 12, 16, 12, 8, 32, 12, 24, 9, 12, 24, 16, 5, 32, 12, 24, 16, 8, 8, 24, 16, 12, 18, 9, 24, 48, 24, 24, 10, 18, 48, 24, 18, 5, 32, 64, 12, 16, 24, 12, 32, 16, 32, 36, 6, 48, 48, 8, 18, 48, 36, 16, 20, 18, 16, 96, 12, 48, 36, 24, 20, 64, 24, 24, 24, 48, 18, 48, 32, 10, 64
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OFFSET

1,3


COMMENTS

The NarumiKatayama index of a connected graph is the product of the degrees of the vertices of the graph.
The MatulaGoebel number of a rooted tree can be defined in the following recursive manner: to the onevertex tree there corresponds the number 1; to a tree T with root degree 1 there corresponds the tth prime number, where t is the MatulaGoebel number of the tree obtained from T by deleting the edge emanating from the root; to a tree T with root degree m>=2 there corresponds the product of the MatulaGoebel numbers of the m branches of T.


REFERENCES

F. Goebel, On a 11correspondence between rooted trees and natural numbers, J. Combin. Theory, B 29 (1980), 141143.
I. Gutman and A. Ivic, On Matula numbers, Discrete Math., 150, 1996, 131142.
I. Gutman and YeongNan Yeh, Deducing properties of trees from their Matula numbers, Publ. Inst. Math., 53 (67), 1993, 1722.
D. W. Matula, A natural rooted tree enumeration by prime factorization, SIAM Review, 10, 1968, 273.
H. Narumi and M. Katayama, Simple topological index. A newly devised index characterizing the topological nature of structural isomers of saturated hydrocarbons, Mem. Fac. Engin. Hokkaido Univ., 16, 1984, 209214.
Z. Tomovic and I. Gutman, NarumiKatayama index of phenylenes, J. Serb. Chem. Soc., 66(4), 2001, 243247.


LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
E. Deutsch, Tree statistics from Matula numbers, arXiv preprint arXiv:1111.4288, 2011
Index entries for sequences related to MatulaGoebel numbers


FORMULA

a(1)=0; a(2)=1; if n = p(t) (the tth prime, t>=2), then a(n)=a(t)*(1+G(t))/G(t); if n=rs (r,s>=2), then a(n)=a(r)*a(s)*G(n)/[G(r)*G(s)]; G(m) denotes the number of prime divisors of m counted with multiplicities. The Maple program is based on this recursive formula.


EXAMPLE

a(7)=3 because the rooted tree with MatulaGoebel number 7 is the rooted tree Y (1*3*1*1=3).
a(2^m) = m because the rooted tree with MatulaGoebel number 2^m is a star with m edges.


MAPLE

with(numtheory): a := proc (n) local r, s: r := proc (n) options operator, arrow: op(1, factorset(n)) end proc: s := proc (n) options operator, arrow: n/r(n) end proc: if n = 1 then 0 elif n = 2 then 1 elif bigomega(n) = 1 then a(pi(n))*(1+bigomega(pi(n)))/bigomega(pi(n)) else a(r(n))*a(s(n))*bigomega(n)/(bigomega(r(n))*bigomega(s(n))) end if end proc: seq(a(n), n = 1 .. 90);


PROG

(Haskell)
import Data.List (genericIndex)
a196063 n = genericIndex a196063_list (n  1)
a196063_list = 0 : 1 : g 3 where
g x = y : g (x + 1) where
y  t > 0 = a196063 t * (a001222 t + 1) `div` a001222 t
 otherwise = a196063 r * a196063 s * a001222 x `div`
(a001222 r * a001222 s)
where t = a049084 x; r = a020639 x; s = x `div` r
 Reinhard Zumkeller, Sep 03 2013


CROSSREFS

Cf. A049084, A020639, A001222, A196065.
Sequence in context: A263856 A090277 A024222 * A205450 A215674 A279211
Adjacent sequences: A196060 A196061 A196062 * A196064 A196065 A196066


KEYWORD

nonn


AUTHOR

Emeric Deutsch, Oct 01 2011


STATUS

approved



