31159

Properties

Appears in sequences

• Join 2n points on a line with n arcs above the line; form graph with the arcs as nodes, joining 2 nodes when the arcs cross. a(n) is the number of cases in which the graph is a path.at n=11A008909
• Number of partitions satisfying 0 < cn(0,5) + cn(1,5) + cn(4,5) + cn(2,5) and 0 < cn(0,5) + cn(1,5) + cn(4,5) + cn(3,5).at n=39A039904
• a(1) = 1; for n >= 1, a(n+1) is smallest number such that the sums of any one, two or three of a(1), ..., a(n) are distinct (repetitions not allowed).at n=26A062065
• a(n) is the n-th prime whose decimal expansion begins with the decimal expansion of n.at n=30A077345
• a(n) = Sum_{k=0..floor(n/8)} binomial(n-5*k, 3*k).at n=29A113032
• Middle of 3 consecutive prime numbers such that p1*p2*p3 + d1 + d2 - 1 = average of twin prime pairs, d1 (delta) = p2 - p1, d2 (delta) = p3 - p2.at n=11A153404
• Primes p such that (p^256 + 1)/2 is prime.at n=21A341234
• Prime numbersat n=3357