27989

Appears in sequences

• Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 15.at n=26A051980
• Smallest composite which when sum of prime factors is repeatedly subtracted reaches a prime after n iterations.at n=34A053093
• Sum of squares of five consecutive primes.at n=18A131686
• Number of nX3 1..2 arrays containing at least one of each value, all equal values connected, and rows considered as a single number in nondecreasing order.at n=29A166781
• Numbers k such that 3^k (mod 2^k) is prime.at n=22A178995
• Number of 9X2 integer matrices with each row summing to zero, row elements in nondecreasing order, rows in lexicographically nondecreasing order, and the sum of squares of the elements <= 2*n^2 (number of collections of 9 zero-sum 2-vectors with total modulus squared not more than 2*n^2, ignoring vector and component permutations).at n=14A192709
• Number of nX2 0..2 arrays with every element value z a city block distance of exactly z from another element value z.at n=5A209470
• Number of nX6 0..2 arrays with every element value z a city block distance of exactly z from another element value z.at n=1A209474
• T(n,k)=Number of nXk 0..2 arrays with every element value z a city block distance of exactly z from another element value z.at n=22A209476
• T(n,k)=Number of nXk 0..2 arrays with every element value z a city block distance of exactly z from another element value z.at n=26A209476
• Solution (a(n)) of the complementary equation a(n) = 2*a(n-1) - a(n-2) + b(n-1) + b(n); see Comments.at n=40A305330