OFFSET
0,1
COMMENTS
FORMULA
a(n+1) = A003415(a(n)), a(0) = 5^6 = 15625.
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 = 5^6; Join[{s}, Table[s = dn[s], {18}]] (* T. D. Noe, Mar 07 2013 *)
PROG
(Haskell)
a129152 n = a129152_list !! n
a129152_list = iterate a003415 15625 -- Reinhard Zumkeller, Apr 29 2012
(PARI) A129152_upto(N)=vector(N, n, N=if(n>1, A003415(N), 5^6)) \\ gives a(0..N-1). To get a(1..N) put A003415() around if() instead inside. M. F. Hasler, Nov 28 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Apr 01 2007
STATUS
approved