21336

Appears in sequences

• Triangle read by rows. T(n, k) = Sum_{i=0..n} Stirling2(n, i)*Product_{j=1..k} (i - j + 1) for 0 <= k <= n.at n=31A059098
• Numbers k such that sigma(x) = k has exactly 10 solutions.at n=30A060666
• Sum of terms of n-th group in A075383.at n=23A075386
• Consider the 1-D random walk with jumps to next-nearest neighbors. Sequence gives number of paths of length n ending at origin.at n=9A092765
• Table T(n,k) read by rows which contains in row n and column k the sum of A001055(A036035(n,j)) over all column indices j where A036035(n,j) has k distinct prime factors.at n=48A093936
• a(n) = index of first appearance of n in A096859.at n=16A097007
• Triangle, read by rows, where T(0,0) = 1, T(n,k) = 2^n*T(n-1,k) + T(n-1,k-1).at n=33A108084
• Numbers that have exactly six prime factors counted with multiplicity (A046306) whose digit reversal is different and also has 6 prime factors (with multiplicity).at n=29A109026
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 0), (1, 0, -1), (1, 1, 1)}.at n=9A149261
• Triangle T(n,m,p,q) = (p^(n-k)*q^k + p^k*q^(n-k))*(StirlingS1(n, k) + StirlingS1(n, n-k)) with p=2 and q=1, read by rows.at n=31A154913
• Triangle T(n,m,p,q) = (p^(n-k)*q^k + p^k*q^(n-k))*(StirlingS1(n, k) + StirlingS1(n, n-k)) with p=2 and q=1, read by rows.at n=32A154913
• Number of -n..n arrays x(0..3) of 4 elements with zero sum and elements alternately strictly increasing and strictly decreasing.at n=20A200058
• Number of ordered triples (w,x,y) with all terms in {-n,...-1,1,...,n} and 2w^2>x^2+y^2.at n=18A211632
• Number of additive Z_2 Z_8 codes of a certain type (see Siap-Aydogdu for precise definition).at n=5A226265
• Number of 2 X 2 0..n arrays with rows and columns in lexicographically nondecreasing order.at n=14A229795
• Number of 2 X 2 matrices with entries in {0,1,...,n} and even determinant with no entry repeated.at n=14A277044
• Numbers whose Euler totient function is equal to the product of the number of divisors of their k first powers, for some k.at n=42A283759
• Check the abundance of a number and iterate the test replacing at every step the sum of the divisors of the previous number. Sequence lists the least numbers whose abundances last n steps.at n=15A286659
• Number of parts in all partitions of n in which no part occurs more than six times.at n=27A320609
• Number of fully chiral set-systems covering n vertices.at n=4A330229