

A088621


a(n) = smallest prime which is a concatenation of 1, n, n^2, n^3, ... n^k for some k, or 0 if no such prime exists.


0



11, 0, 13, 0, 0, 0, 17, 0, 19, 0, 111121, 0, 113, 0, 0, 0
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OFFSET

1,1


COMMENTS

a(2n)=a(5n)=0. Next term a(17) has 176 digits (k=16) and is too large to include in sequence. a(19), if it exists, has k>100.  Ray Chandler, Oct 18 2003


LINKS



EXAMPLE

a(11) = 111121 which is a concatenation of 1, 11 and 121. value of k = 2.


MATHEMATICA

f[n_] := Block[{k = FromDigits[Join[{1}, IntegerDigits[n]]], e = 1}, While[ !PrimeQ[k], e++; k = FromDigits[Join[IntegerDigits[k], IntegerDigits[n^e]]]]; k]; g[n_] := If[ Mod[n, 10] == 1  Mod[n, 10] == 3  Mod[n, 10] == 7  Mod[n, 10] == 9, f[n], 0]; Table[ g[n], {n, 1, 17}] (* Robert G. Wilson v *)


CROSSREFS



KEYWORD

base,nonn


AUTHOR



STATUS

approved



