2290792932

Appears in sequences

• Subfactorial or rencontres numbers, or derangements: number of permutations of n elements with no fixed points.at n=13A000166
• a(n) = floor( n! / e ).at n=12A014508
• The subfactorial with index prime(n).at n=5A161744
• The subfactorial with index Fibonacci(n).at n=7A161745
• Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by nine: p(i)<>i and (i-p(i) mod n <= 9 or p(i)-i mod n <= 9).at n=13A257953
• Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by seven: p(i)<>i and (i-p(i) mod n <= 7 or p(i)-i mod n <= 7).at n=13A260091
• Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by six: p(i)<>i and (i-p(i) mod n <= 6 or p(i)-i mod n <= 6).at n=13A260111
• Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by eight: p(i)<>i and (i-p(i) mod n <= 8 or p(i)-i mod n <= 8).at n=13A260115
• Number of permutations p of [n] with no fixed points and cyclic displacement of elements restricted by ten: p(i)<>i and (i-p(i) mod n <= 10 or p(i)-i mod n <= 10).at n=13A260216
• Triangle read by rows: T(n-1,k), where n >= 2 and 1 <= k <= floor(n/2), is the number of permutations of (1, 2, ..., n) having k consecutive pairs but no consecutive sequences of length greater than 2.at n=36A289632
• a(n) = A000166(floor(n/2)) if n is even otherwise A000240(floor((n + 1)/2)).at n=26A371998