220500

Appears in sequences

• Number of rooted 2-dimensional polyominoes with n pentagonal cells, with no symmetries removed.at n=7A051738
• Matrix product of Stirling2-triangle A008277(n,k) and unsigned Stirling1-triangle |A008275(n,k)|.at n=40A079641
• OU-Sigma multiperfect numbers.at n=10A091321
• Array read by antidiagonals: T(n,k) = number of rooted 2-dimensional polyominoes with k cells, the cells being regular n-gons, with no symmetries removed.at n=52A094166
• Duplicate of A051738.at n=7A094167
• Triangle of coefficients of square of Hermite polynomials divided by 2^n with argument sqrt(x/2).at n=38A111595
• Third column (m=2) of unsigned triangle A111595.at n=6A111602
• T(n, k) = [x^k] Sum_{k=0..n} Stirling2(n, k)*RisingFactorial(x, k), triangle read by rows, for n >= 0 and 0 <= k <= n.at n=50A129062
• Seventh column of triangle A035342.at n=3A132052
• Partition number array, called M31(5), related to A049353(n,m)= |S1(5;n,m)| (generalized Stirling triangle).at n=32A144355
• Symmetrical Hahn weights on q-form factorials:m=2;q=3; q-form:t(n,m)=If[m == 0, n!, Product[Sum[(m + 1)^i, {i, 0, k - 1}], {k, 1, n}]]; Hahn weight:b(n,k,m)=If[n == 0, 1, (n!*t[m + 1, k]*t[m + 1, n - k])/(k!*(n - k)!*t[1, n])].at n=24A157321
• Triangle T(n, k) = (n+2)*c(n+2)*f(n+2)/(f(n-k+1)*f(k+1)) where f(n) = c(n)/(n*c(n-1)), c(n) = (n-3)! for n>2 and 1 otherwise, read by rows.at n=40A171830
• Numbers with prime factorization p^2*q^2*r^2*s^3 where p, q, r, and s are distinct primes.at n=3A190382
• Triangular array read by rows. T(n,k) is the number of simple labeled graphs on n nodes with no isolated nodes and exactly k components. n >= 2, 1 <= k < n/2.at n=23A218334
• From higher-order arithmetic progressions.at n=4A259457
• Exponential Riordan array [Bessel_I(0,2*x)^2, x].at n=57A282252
• Numbers k such that k and usigma(k) have the same set of prime divisors, where usigma(k) is the sum of unitary divisors of k (A034448).at n=39A329858
• Numbers having exactly four non-unitary prime factors.at n=8A338541
• a(n) is the smallest integer that has exactly n divisors from A333369.at n=28A355771
• Positions of records in A355770.at n=19A355772