OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..1000 (first 300 terms from Vincenzo Librandi)
EXAMPLE
a(1) = 3 because 31 = 3*10 + 1 is the smallest prime of form p*10 + 1, where p is a prime.
a(2) = 7 because 701 = 7*100 + 1 is the smallest prime of form p*100 + 1.
MAPLE
Primes:= select(isprime, [$1..10^5]):
for n from 1 to 1000 do
for p in Primes do
if isprime(p*10^n+1) then
A[n]:= p
fi
od
od:
seq(A[n], n=1..1000); # Robert Israel, May 29 2014
MATHEMATICA
prs=Prime[Range[2000]]; Table[i=1; While[!PrimeQ[First[Take[prs, {i}]] 10^n+1], i++]; Prime[i], {n, 200}] (* Harvey P. Dale, May 15 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, Aug 15 2006
STATUS
approved