18473

Appears in sequences

• a(n) = T(n,1) + T(n-1,2) + ...+ T(n-k+1,k), where k = floor((n+1)/2) and T is the array defined in A026098.at n=44A026103
• a(n) = C(3+n, n) + C(4+n, n) + C(5+n, n) + C(6+n, n).at n=11A062966
• Piet Hut's "coat-hanger" sequence: unlabeled forests of rooted trees with n edges, where there can be any number of components, the outdegree of each node is <= 2 and the symmetric group acts on the components.at n=14A088325
• Bisection of A000125.at n=24A100503
• a(n) = binomial(n,4) - binomial(floor(n/2),4) - binomial(ceiling(n/2),4).at n=28A111385
• Numbers m such that A137671(m) = 1.at n=12A137674
• Number of steps to go from (n+1)!-1 to n!-1 with map x -> x - (sum of digits in factorial base representation of x).at n=7A219661
• -7-Knödel numbers.at n=20A225511
• Numbers for which the root mean square of nontrivial divisors is an integer and which are not a square of prime numbers.at n=33A247137
• Decimal representation of the x-axis, from the left edge to the origin, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 579", based on the 5-celled von Neumann neighborhood.at n=16A283089
• a(n) is the smallest prime(n)-rough number k that has more divisors than k-1 and more divisors than k+1.at n=3A347719
• Terms of A349937 that are not divisible by 3: numbers k > 1 not divisible by 2 or 3 such that A309906(k-1) < A309906(k) > A309906(k+1).at n=8A349941