|
|
A267237
|
|
Numbers n such that 'n-1' 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
|
|
|
|