

A267237


Numbers n such that 'n1' prepended to 'n' n times yield primes.


1




OFFSET

1,1


COMMENTS

a(5) produces the prime: 4182...[4183 times]4183 (16736 digits).


LINKS



EXAMPLE

7 occurs because '6' prepended 7 times to '7' produces prime (66666667).


MATHEMATICA

Select[ Range[1200], PrimeQ[ FromDigits[ StringJoin@@ ToString/@ PadLeft[{#}, #+1, #1]]] &]


CROSSREFS



KEYWORD

nonn,more,hard


AUTHOR



STATUS

approved



