21710

Appears in sequences

• Number of 5-tuples of different integers from [ 1,n ] with no common factors among quadruples.at n=21A015644
• Number of 5-tuples of different integers from [ 2,n ] with no common factors among quadruples.at n=21A015645
• Numbers k such that 53*2^k-1 is prime.at n=16A050552
• Squares where knight moving to a lowest unvisited square on a spirally numbered board will have no available moves.at n=13A323714