121487

Properties

Appears in sequences

• Counting sequence for classification of nonattacking queens on n X n toroidal board.at n=30A054502
• Let P(A) be the power set of an n-element set A. Then a(n) = the number of pairs of elements {x,y} of P(A) for which either 0) x and y are intersecting but for which x is not a subset of y and y is not a subset of x, or 1) x and y are intersecting and for which either x is a proper subset of y or y is a proper subset of x, or 2) x = y.at n=9A134064
• Primes of the form k*(k+1)*(k+2)/6+2 (i.e., two more than a tetrahedral number).at n=12A221055
• Numbers k such that (7*10^k + 143)/3 is prime.at n=30A271585
• Numbers k such that A007908(k) == 1 (mod k).at n=1A362966
• Prime numbersat n=11433