OFFSET
0,3
EXAMPLE
For n = 33: a(33) = 6561 because for the number 33 there are 4 steps of defined iteration: {3^3 = 27}, {7^2 = 49}, {9^4 = 6561}, {((1^6)^5)^6 = 1} and the 3rd step of the iteration ends with 6561.
MAPLE
A175420 := proc(n) option remember; local dgs, a, i ; if n = 0 then return 0 ; end if; dgs := convert(n, base, 10) ; a := op(1, dgs) ; for i from 2 to nops(dgs) do a := a^ op(i, dgs) ; end do: a ; end proc:
for n from 0 do printf("%d, \n", A175422(n)) ; end do; # R. J. Mathar, May 12 2010
MATHEMATICA
Unprotect[Power]; Power[0, 0] = 1; Protect[Power]; A175420[0]=0; A175420[n_]:=If[(len=IntegerLength[n])==1, n, Last[list=IntegerDigits[n]]^Product[Part[Drop[list, -1], i], {i, len-1}]]; a[n_]:=Nest[A175420[#]&, n, 3]; Array[a, 70, 0] (* Stefano Spezia, Feb 25 2024 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, May 09 2010
EXTENSIONS
7 more terms from R. J. Mathar, May 12 2010
STATUS
approved