login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A146892 For definition see comments lines. 3
1, 6, 6, 72, 72, 72, 6, 72, 72, 5184, 6, 5184, 72, 5184, 31104, 5184, 5184, 5184, 2592, 5184, 432, 373248, 36, 373248, 31104, 26873856, 26873856, 26873856, 373248, 31104, 36, 31104, 2239488, 2239488, 1934917632, 26873856, 31104, 2239488 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Let USigma denote the unitary sigma function, A034448.

As in A146891, let PF_p(n) denote the largest power of the prime p dividing n. PF_2 is A006519, and PF_3 is A038500. Furthermore define PF_1(n)=1.

Extension to multi-prime-indices is done by multiplying the corresponding functions: PF_{p,q,..}(n) = PF_p(n)*PF_q(n)*... An example of this is PF_{2,3} = A065331.

[How to compute c(m)]

Case of Base Primes = {2}{3}

c(0)=2^m, b(0)=2^m

c(n)=c(n-1)/PF_2[USigma[b(n-1)]]*PF_3[USigma[b(n-1)]]

b(n)=USigma[b(n-1)]/ PF_2,3[USigma[b(n-1)]]

IF b(k)=1 THEN END

a(m)=c(k)

Sequence gives a(m)

Factorization of term becomes 2^r*3^s.

LINKS

Table of n, a(n) for n=0..37.

MAPLE

A146892 := proc(n) local b, a, k ;

   b := [2^n] ;

   while op(-1, b) <> 1 do

       b := [op(b), A065330(A034448(op(-1, b))) ] ;

   od:

   a := 2^n ;

   for k from 2 to nops(b) do

       a := a/ A006519(A034448(op(k-1, b))) *A038500(A034448(op(k-1, b))) ;

   od:

   a ;

end: # From R. J. Mathar, Jun 24 2009]

CROSSREFS

Cf. A146891.

Sequence in context: A269888 A269767 A065239 * A085804 A012125 A267139

Adjacent sequences:  A146889 A146890 A146891 * A146893 A146894 A146895

KEYWORD

nonn,uned

AUTHOR

Yasutoshi Kohmoto, Apr 17 2009

EXTENSIONS

More terms from R. J. Mathar, Jun 24 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified May 24 22:11 EDT 2017. Contains 287008 sequences.