OFFSET
1,1
COMMENTS
Terms from Robert G. Wilson v.
EXAMPLE
a(1) = 9 as 1 (19 times) = (10^19-1)/9 is the smallest prime of this form with an odd number of 1's.
a(2) = 2 as 12421 is a prime.
MATHEMATICA
Do[k = 0; While[a = Table[n^i, {i, 0, k}]; b = ToExpression[ StringJoin[ ToString /@ Join[a, Drop[ Reverse[a], 1]]]]; !PrimeQ[b], k++ ]; Print[k], {n, 1, 10} ] (* Robert G. Wilson v *)
CROSSREFS
KEYWORD
more,nonn,base
AUTHOR
Ray Chandler and N. J. A. Sloane, Apr 08 2014
STATUS
approved