27679

Appears in sequences

• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 17 ones.at n=33A031785
• Numbers n such that "n 42's followed by 43" is prime.at n=16A110705
• Numbers k such that 23^k + 2 is prime.at n=6A138050
• Number of nX6 0..1 arrays with every element unequal to 0, 1, 3, 6 or 8 king-move adjacent elements, with upper left element zero.at n=8A305480
• Semiprimes k such that k is congruent to 7 modulo k's index in the sequence of semiprimes.at n=5A356357
• Draw a regular n-gon and the enclosing circle, then for each pair of vertices X, Y, draw a circle with diameter XY; the union of these figures is the graph H_n; sequence gives number of regions in H_n.at n=20A370978