19997

Properties

Appears in sequences

• Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 19.at n=32A050968
• Engel expansion of zeta(9)=sum(i>0,1/i^9).at n=5A067917
• Primes related to the nondecreasing subsequence of A007605 (sums of digits of primes).at n=42A067954
• Primes with either no internal digits or all internal digits are 9.at n=51A069684
• a(n) = smallest k such that 4k has a digit sum = n.at n=40A077490
• Primes with digit sum = 35.at n=4A106770
• a(n) = Sum_{k + l*m <= n} (k + l*m), with 0 <= k,l,m <= n.at n=21A106846
• Primes p such that p's set of distinct digits is {1,7,9}.at n=21A108384
• Least n-digit prime which differs from the next prime at every corresponding digit.at n=4A114016
• Largest prime < 10000*a(n-1), a(1)=2.at n=1A124364
• a(n) = (n^5-n-5)/5.at n=10A134327
• Primes congruent to 55 mod 59.at n=39A142782
• Primes congruent to 50 mod 61.at n=38A142848
• Primes p of the form 4*k+1 for which s=26 is the least positive integer such that s*p-(floor(sqrt(s*p)))^2 is a square.at n=23A145050
• Primes containing 999 as a substring.at n=7A167292
• Primes of the form 2*10^k - 3.at n=3A177135
• Integers k such that 2^(k-1) == 1 (mod k) and 2^(m-1) == 1 (mod m), where m = k*(A000265(k-1) - 1) + 1 and A000265 gives the odd part of its argument.at n=15A187849
• Primes of the form 2n^2 - 3.at n=25A201712
• Primes of the form 8n^2 - 3.at n=12A201856
• Primes of the form 15*k^2 - 15*k + 17.at n=26A220081