A146891 -id:A146891 - cp's OEIS frontend

A146892 For definition see comments lines.

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

Offset: 0

Yasutoshi Kohmoto, Apr 17 2009

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.

Cf. A146891.

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: # R. J. Mathar, Jun 24 2009

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

cp's OEIS Frontend

A146892 For definition see comments lines.

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