133920

Appears in sequences

• Number of squares (of another matrix) in the group GL(2,Z_n) described in sequence A000252.at n=36A068516
• Balanced refactorable numbers.at n=13A078543
• Triangle read by rows: T(n,k) = the number of ascending runs of length k in the permutations of [n] for k <= n.at n=49A122843
• a(n) = (9/2)*(n-1)*(n-2)*(n-3).at n=32A134171
• Triangle T(n,k), 1 <= k <= n, read by rows: T(n,k) is the number of permutations in the symmetric group S_n having k multiplicative 3-excedances. Equivalently, the number of permutations of the set {3,6,9,...,3n} with k excedances.at n=42A136717
• Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k entries divisible by 3 that are followed by a smaller entry (n>=1, k>=0).at n=18A136718
• Numbers n such that sigma(n) = 14*phi(n) (where sigma=A000203, phi=A000010).at n=10A171259
• The sum of the two numbers in an amicable pair, A002025(n) + A002046(n).at n=9A180164
• Numbers with prime factorization pqr^3s^5.at n=17A190475
• a(n) = 10*a(n-1) + 8*a(n-2), with a(0)=0, a(1)=1.at n=6A190957
• Number of ascending runs of length n in the permutations of [2n].at n=5A230382
• The sum (in nondecreasing order) of the two numbers in an amicable pair.at n=8A259953
• Three-column table read by rows: Triples that have the same value of phi, sigma, and tau.at n=9A322679
• Three-column table read by rows: Primitive distinct triples that have the same value of phi, sigma, and tau.at n=9A322689
• Triangular array read by rows: row n shows the coefficients of the polynomial p(x,n) constructed as in Comments; these polynomials form a strong divisibility sequence.at n=18A327323