18211

Properties

Appears in sequences

• Primes p such that p, p+6, p+12, p+18 are all primes.at n=33A023271
• Initial prime in set of 4 consecutive primes with common difference 6.at n=13A033451
• First term of balanced prime quartets: p(m+1)-p(m) = p(m+2)-p(m+1) = p(m+3)-p(m+2).at n=13A054800
• Discriminants of imaginary quadratic fields with class number 25 (negated).at n=30A056987
• Primes which yield a prime whenever a 1 is inserted anywhere in them (including at the beginning or end).at n=24A069246
• Primes p such that the differences between the 5 consecutive primes starting with p are (6,6,6,4).at n=2A078969
• Primes p such that p, p+6, p+12, p+18 are consecutive primes and p = 6*k+1 for some k.at n=5A090837
• Primes arising as A093929(n)*A093929(n+1)+2.at n=26A093930
• Prime mean of 8 horizontal, vertical and main diagonal sums associated with primes in A094454.at n=22A094455
• Number of rooted planar trees in which no branch is identical to its adjacent neighbor.at n=12A106362
• Triangular array: T(n,k) = T(n,n) = 1, T(n,k) = 5*T(n-1, k-1) + 2*T(n-1, k), read by rows.at n=31A119727
• Number of 2-anisohedral polyominoes of order n.at n=19A120646
• Expansion of q / (chi(-q) * chi(-q^11))^2 in powers of q where chi() is a Ramanujan theta function.at n=30A123631
• Primes congruent to 32 mod 53.at n=38A142562
• Primes congruent to 39 mod 59.at n=33A142766
• Primes congruent to 33 mod 61.at n=36A142831
• Greater of two consecutive primes, p < q, such that both p*q+p-q and p*q-p+q are prime numbers.at n=26A154552
• Number of permutations of 1..n containing the relative rank sequence { 254613 } at any spacing.at n=3A159165
• Number of permutations of 1..n containing the relative rank sequence { 326514 } at any spacing.at n=3A159172
• Numbers n such that 10^n - 71 is prime.at n=21A178434