19991

Properties

Appears in sequences

• Palindromic primes: prime numbers whose decimal expansion is a palindrome.at n=45A002385
• Primes that contain digits 1 and 9 only.at n=11A020457
• Primes that remain prime through 3 iterations of function f(x) = 9x + 4.at n=37A023297
• Greater of two consecutive palindromes, both of which are prime.at n=11A032594
• Palindromic and prime Fibonacci-lucky numbers.at n=21A039679
• Palindromic primes containing at least one pair of consecutive equal digits.at n=6A050786
• Palindromic Sophie Germain primes.at n=9A051835
• Primes at which the difference pattern X24Y (X and Y >= 6) occurs in A001223.at n=36A052163
• Palindromic primes of the form 'primemirp' resulting from A054217.at n=11A054218
• Palindromic primes using only two distinct digits and only the exterior digit is different.at n=18A056728
• Palindromic primes with just two distinct digits.at n=21A056730
• Smallest palindrome with digit sum = n.at n=29A062388
• Floor[X/Y] where X = concatenation in increasing order of first n even numbers and Y = that of first n natural numbers.at n=7A067096
• Primes in which a string of 9's is sandwiched between two 1's.at n=2A068649
• Primes which are a sandwich of numbers using at most one digit between two 1's.at n=9A068685
• Let p = abc..k be a prime in base 10. Define mirror(p) = abc...k...cba. Sequence gives primes of the form mirror(p) for some p.at n=13A068686
• Primes with either no internal digits or all internal digits are 9.at n=49A069684
• Smallest palindromic prime with digit sum = n, or 0 if no such prime exists.at n=28A070245
• Palindromic primes with nonprime middle digit.at n=22A076613
• Palindromes k such that k + 11 is also a palindrome.at n=24A082275