31687

Properties

Appears in sequences

• Number of matchings in graph P_{3} X P_{n}.at n=6A033506
• Number of matchings in graph P_{6} X P_{n}.at n=3A033509
• Primes of the form k^2 + 3.at n=29A049423
• Let n range through the odd numbers skipping multiples of 5; a(n) = n-th prime ending in n.at n=34A089779
• Duplicate of A049423.at n=29A121825
• Primes p such that 2p + 3, 4p + 9, 3p + 2 and 9p + 8 are also primes.at n=18A176619
• Number of fixed tree-like convex polyominoes.at n=12A196593
• Triangle read by rows: T(n,k) (1 <= k <= n) = number of monomer-dimer tilings of an n X k board.at n=17A210662
• In the '3x+1' problem, primes which as starting values set new records for number of steps to reach 1, where a step means either 'divide by two' or 'triple plus one and then divide by two'.at n=24A244638
• a(n) is the first prime p such that the sum of 2*n consecutive primes starting at p is (q-1)*q where q is prime, or 0 if there is no such p.at n=45A338990
• Prime numbersat n=3408