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A175423
Sequence of numbers after 4th step of iteration defined in A175419.
8
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 4, 9, 6, 25, 216, 1, 1, 1, 0, 1, 8, 1, 1, 25, 36, 1, 8, 1, 0, 1, 6, 1, 1, 1, 1, 1, 1, 1, 0, 1, 8, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 8, 1, 1, 1, 1, 1, 1, 1, 1
OFFSET
0,3
EXAMPLE
For n = 33: a(33) = 1 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 4th step of iteration ends with 1. - Jaroslav Krizek, May 09 2010
MAPLE
A175420 := proc(n) option remember; local dgs, a, i ; if n = 0 then return 0 ; end if; dgs := convert(n, base, 10) ; if op(1, dgs)= 0 then return 0 ; end if; for i from 1 to nops(dgs) do if op(-i, dgs) = 0 then dgs := [op(-i..nops(dgs), dgs)] ; dgs := subsop(1=1, dgs) ; break ; end if; end do: a := op(1, dgs) ; for i from 2 to nops(dgs) do a := a^ dgs[i] ; end do: a ; end proc:
A175421 := proc(n) A175420(A175420(n)) ; end proc:
A175422 := proc(n) A175420(A175421(n)) ; end proc:
A175423 := proc(n) A175420(A175422(n)) ; end proc:
seq(A175423(n), n=0..100) ; # 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, 4]; Array[a, 101, 0]
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, May 09 2010
EXTENSIONS
More terms from R. J. Mathar, May 12 2010
a(100) corrected by Stefano Spezia, Feb 25 2024
STATUS
approved