21820

Appears in sequences

• Number of basis partitions of n+81 with Durfee square size 9.at n=25A069252
• Values of k such that the total number of 1's in the binary expansions of the first k integers is a multiple of k.at n=26A095376
• E.g.f.: exp(x + 3/2*x^2).at n=8A115327
• Triangle read by rows: T(n,k) is the number of length n left factors of Dyck paths having k DUU's, where U=(1,1) and D=(1,-1).at n=60A191795
• Triangle read by rows: T(n,k) is the number of subpermutations of an n-set whose orbits are each of size at most k, and without fixed points. Equivalently, T(n,k) is the number of partial derangements of an n-set each of whose orbits is of size at most k.at n=38A261762
• Number of partitions of n into colored blocks of equal parts, such that all colors from a set of size six are used and the colors are introduced in increasing order.at n=18A327289
• a(0) = 1, a(1) = 0, a(2) = 1; a(n) = a(n-1) + Sum_{k=0..n-3} a(k) * a(n-k-3).at n=18A357307
• Number of isomorphism classes k of groups G of order p*2^n when G contains a unique Sylow p subgroup and the maximal 2^m dividing p-1 is such that 2^m >= 2^n.at n=7A376349
• a(n) = 25*n^2/2 - 11*n/2 + 1.at n=42A383465