OFFSET
0,3
EXAMPLE
For n = 33: a(33) = 49 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 2nd step of the iteration ends with 49.
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_]:=A175420[A175420[n]]; Array[a, 51, 0] (* Stefano Spezia, Feb 25 2024 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, May 09 2010
STATUS
approved