OFFSET
0,1
COMMENTS
FORMULA
a(n+1) = A003415(a(n)), a(0) = 3^4 = 81.
MATHEMATICA
dn[0] = 0; dn[1] = 0; dn[n_?Negative] := -dn[-n]; dn[n_] := Module[{f = Transpose[FactorInteger[n]]}, If[PrimeQ[n], 1, Total[n*f[[2]]/f[[1]]]]]; s = 3^4; Join[{s}, Table[s = dn[s], {25}]] (* T. D. Noe, Mar 07 2013 *)
PROG
(Haskell)
a129151 n = a129151_list !! n
a129151_list = iterate a003415 81 -- Reinhard Zumkeller, Apr 29 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 01 2007
STATUS
approved