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A234967 Smallest zeroless number such that a(n)^n has at least one zero. 0
32, 16, 7, 4, 4, 8, 5, 6, 2, 2, 2, 4, 5, 3, 3, 2, 3, 4, 2, 2, 2, 2, 4, 3, 2, 4, 4, 2, 2, 4, 3, 3, 4, 3, 3, 3, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

It is very probable that a(n) = 2 for n > 87.

LINKS

Table of n, a(n) for n=2..74.

EXAMPLE

7 is the smallest number with nonzero digits such that 7^4 has at least one zero, so a(4) = 7.

MATHEMATICA

m[n_] := Min@ IntegerDigits@n; a[1]=0; a[n_] := Block[{k=2}, While[m[k] == 0 || m[k^n] > 0, k++]; k]; Array[a, 70] (* Giovanni Resta, Jan 11 2014 *)

PROG

(Python)

def f(x):

..for n in range(10**7):

....if str(n).find("0") == -1:

......if str(n**x).find("0") > -1:

........return n

x = 1

while x < 75:

..if f(x) == None:

....print(0)

..else:

....print(f(x))

..x += 1

CROSSREFS

Cf. A052382.

Sequence in context: A097614 A069892 A070621 * A033352 A140387 A023094

Adjacent sequences:  A234964 A234965 A234966 * A234968 A234969 A234970

KEYWORD

nonn,base

AUTHOR

Derek Orr, Jan 02 2014

STATUS

approved

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Last modified October 20 22:44 EDT 2019. Contains 328291 sequences. (Running on oeis4.)