22935

Appears in sequences

• Number of ways of placing n labeled balls into 3 indistinguishable boxes with at least 2 balls in each box.at n=5A000478
• Numbers k such that phi(k) = phi(k+1).at n=21A001274
• Number of partially achiral rooted trees.at n=16A003240
• Numbers k such that the multiplicative group of residues prime to k, M_k, is isomorphic to M_{k+1}.at n=6A003276
• Triangle T(n,k) of associated Stirling numbers of second kind, n >= 2, 1 <= k <= floor(n/2).at n=27A008299
• Discriminants of quintic fields with 2 complex conjugates (negated).at n=42A023684
• Numbers whose set of base-12 digits is {1,3}.at n=37A032919
• Positive integers n such that phi(n) - d(n) = phi(n+1) - d(n+1) where d(n) is the number of divisors of n.at n=5A063069
• Squarefree numbers k such that phi(k) = phi(k+1).at n=11A063739
• Numbers n such that |phi(n+1)-phi(n)| = |d(n+1)-d(n)|, where phi is Euler's totient function and d(n) = number of divisors of n.at n=10A066219
• Triangle of Ward numbers T(n,k) read by rows.at n=30A134991
• Numbers k such that lambda(k) = lambda(k+1).at n=22A173695
• Triangle of Ward numbers T(n,k) (n>=0, k=0 if n=0, otherwise 0 <= k <= n-1) read by rows.at n=34A181996
• The number of set partitions of {1,2,...,n} into a prime number of blocks each of which contains a prime number of elements.at n=7A190529
• Numbers n such that tau(n) = tau(n+1) and phi(n) = phi(n+1).at n=2A217773
• Number of proper colorings of the cube with at most n colors under rotational symmetry.at n=11A249460
• Numbers n such that phi(n) + d(n) = phi(n+1) + d(n+1), where phi(n) is the Euler totient function of n and d(n) the number of divisors of n.at n=7A259496
• Triangle read by rows, Ward numbers T(n, k) = Sum_{m=0..k} (-1)^(m + k) * binomial(n + k, n + m) * Stirling2(n + m, m), for n >= 0, 0 <= k <= n.at n=39A269939
• Number of quadrilateral regions in an equilateral triangular "frame" of size n (see Comments in A328526 for definition).at n=16A333033
• Regular triangle read by rows. T(n, k) = {{n, k}}, where {{n, k}} are the second order Stirling set numbers (or second order Stirling numbers). T(n, k) for 0 <= k <= n.at n=69A358623