119191

Properties

Appears in sequences

• Primes that contain digits 1 and 9 only.at n=19A020457
• Concatenate (1,n,n,1).at n=19A100846
• Primes of the concatenated form 1nn1 where n is an integer >=0.at n=3A102497
• Emirps with digits 1 and 9 only.at n=6A155507
• Lesser of emirps (pairs) with digits 1 and 9 only.at n=4A155508
• Primes such that the decimal digits in the first half of the number are a nontrivial permutation of the digits in the second half.at n=4A297994
• Invertible primes p such that k*p - 1 and k*p + 1 is a twin prime pair; for k = 12.at n=11A317029
• Primes p such that exactly five numbers among all circular permutations of the digits of p are prime.at n=27A344629
• a(n) = 1 + Sum_{k=0..floor((n-1)/2)} a(k) * a(n-2*k-1).at n=18A351972
• Prime numbersat n=11233