217800

Appears in sequences

• Generalized tangent numbers of type 3^(2n+1).at n=2A005801
• Non-palindromic numbers such that either x=q1.Rev[x] or Rev[x]=q2.x, where R[x]=A004086[x] and q1 or q2 are integers not divisible by 10.at n=36A071687
• Lah numbers: a(n) = n!*binomial(n-1,8)/9!.at n=3A111599
• Let df(n,k) = Product_{i=0..k-1} (n-i) be the descending factorial and let P(m,n) = df(n-1,m-1)^2*(2*n-m)/((m-1)!*m!). Sequence gives P(8,n).at n=11A132466
• Triangle read by rows: number of nilpotent partial transformations (of an n-element set) of height r (height(alpha) = |Im(alpha)|), 0 <= r < n.at n=38A141618
• Numbers with prime factorization p^2*q^2*r^2*s^3 where p, q, r, and s are distinct primes.at n=2A190382
• a(n) = RF(n+1,3)*C(n+2,n-1), where RF(a,n) is the rising factorial.at n=9A253285
• Numbers n such that 2^n == 1 (mod sigma(n)).at n=36A278836
• Coefficients T(n,k) of x^n*y^(n-k)*z^k in function A = A(x,y,z) such that A = 1 + x*B*C, B = 1 + y*C*A, and C = 1 + z*A*B, as a triangle read by rows.at n=40A323324
• The number of regions inside a decagon formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.at n=4A333139
• Numbers having exactly four non-unitary prime factors.at n=7A338541
• Least k >= 1 such that sigma(k)/tau(k) has denominator n or zero if no k exists.at n=35A346644
• Number T(n,k) of partitions of [n] for which the difference between the longest and the shortest block size is k; triangle T(n,k), n>=0, 0<=k<=max(0,n-2), read by rows.at n=50A364971
• Primitive exponential unitary abundant numbers: the powerful terms of A383693.at n=35A383694
• Primitive exponential squarefree exponential abundant numbers: the powerful terms of A383697.at n=32A383698
• Primitive exponential admirable numbers: the powerful terms in A336680.at n=29A391283