66780

Appears in sequences

• a(n) = [ a(n-1)/a(1) + a(n-3)/a(3) + a(n-5)/a(5) + ... ], for n >= 3.at n=35A022865
• Saint-Exupéry numbers: ordered products of the three sides of Pythagorean triangles.at n=24A057096
• Ordered products of the sides of primitive Pythagorean triangles.at n=9A063011
• a(n) is the number of odd permutations (of an n-set) with exactly 1 fixed point.at n=8A145222
• Triangle read by rows: T(n,k) is the number of odd permutations (of an n-set) with exactly k fixed points.at n=46A145225
• Triangle read by rows: T(n,k) is the number of permutations of [n] with k circular successions (0<=k<=n-1). A circular succession in a permutation p of [n] is either a pair p(i), p(i+1), where p(i+1)=p(i)+1 or the pair p(n), p(1) if p(1)=p(n)+1.at n=38A180188
• Diagonal sums of number triangle A114709.at n=9A186940
• Numbers k such that sigma(k) = 3*sigma(k+1).at n=4A217791
• Triangle read by rows: coefficients xi(n,k) arising from the study of completely transitive graphs on n nodes.at n=18A259971
• Triangle T(n,k) read by rows: the number of independent sets of size k in the 132 core of size n.at n=41A278390
• Number of 9-regular cubic partitions of n.at n=32A335604
• Partition the integers from 1 to n into three groups with consecutive numbers, then a(n) is the maximum value of the sum of the numbers in the second group multiplied by the minimum of the sum of the numbers in the first and third groups.at n=35A342713
• Triangle read by rows: T(n,k) is the number of permutations in symmetric group S_n with (n-k) fixed points and an odd number of non-fixed point cycles. Equivalent to the number of cycles of n items with cycle type defined by non-unity partitions of k <= n that contain an odd number of parts.at n=53A373418