30809

Properties

Appears in sequences

• Primes that remain prime through 4 iterations of function f(x) = 10x + 3.at n=9A023328
• Primes of the form k^2 + k + 9.at n=20A027758
• a(n) = Sum{a(k): k=0,1,2,...,n-4,n-2,n-1}; a(n-3) is not a summand; initial terms are 0,1,2.at n=18A049858
• Primes p such that 8p +1 and (p-1)/8 are primes.at n=14A085958
• Primes which remain prime after one and after two applications of the rotate-and-add operation of A086002.at n=25A086003
• Numbers k such that 2^k + 3^k + 5^k + 7^k is a prime number.at n=6A114301
• Prime numbers obtained by inserting a 0 between each pair of adjacent digits of a prime number > 10.at n=32A119680
• Primes which are the sum of the first k nonprimes for some k >= 2.at n=24A128927
• Row sums of triangle A131402.at n=14A131403
• Primes p such that p,q,r,s are consecutive primes and 2p+9, 2q+9, 2r+9, 2s+9 are also primes.at n=7A190354
• Integer k associated with the conjectured record-breaking maximal value A226665(n) of the minimal elements of primitive Collatz-like 3x+k cycles.at n=11A226666
• Integer k associated with the conjectured record-breaking maximal element A226667(n) of primitive Collatz-like 3x+k cycles.at n=10A226668
• Total number of congruence subgroups of PSL(2,Z) of genus n.at n=16A258691
• Primes p such that p plus the cube of sum of digits of p is a perfect square.at n=16A259418
• Primes p such that p+2^3, p+2^5 and p+2^7 are all primes.at n=41A275475
• Primes, starting with a(1)=2, whose successive differences are increasing triangular numbers.at n=19A278139
• Primes whose decimal expansion is of the form d_1+0+d_2+0+d_3+0+...+0+d_k where d_i are digits with 1 <= d_i <= 9, k > 1 and + stands for concatenation.at n=43A309488
• First of three consecutive primes p,q,r such that p+q, p+r and q+r are all triprimes.at n=13A362203
• Number of linear connected animals formed from n 4-gon or 6-gon connected truncated octahedra.at n=7A363210
• Prime numbers p such that (2*p)# - p# + 1 is prime, where p# = A034386(p).at n=11A379380