21981

Appears in sequences

• Least k such that the first k terms of A006928 contain n more 2's than 1's.at n=12A025507
• Numbers having four 3's in base 9.at n=7A043468
• Column 7 of triangle A055898.at n=5A055903
• Smallest k>n such that n^3+1 divides k*n^2+1.at n=28A071568
• A Jacobsthal convolution.at n=16A113726
• Number of 2 X n arrays of the minimum value of corresponding elements and their horizontal, vertical or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..3 2 X n array.at n=16A220205
• Expansion of Product_{k>=1} (1+x^k)^(A000129(k)).at n=11A261331
• Indices in A006928 where the imbalance between 1's and 2's sets a new record.at n=25A274775
• Number of ways to write n as an ordered sum of 6 prime power palindromes (A084092).at n=38A282845
• The number of hanging vertically stable self-avoiding walks of length n on a 3D cubic lattice where both the nodes and connecting rods have mass.at n=13A337761
• G.f. satisfies A(x) = 1 + x*A(x)^2*(1 + x^3*A(x)).at n=10A365267