21085

Appears in sequences

• Expansion of Product_{m>=1} (1 - m*q^m)^5.at n=18A022665
• Number of consecutive runs of 3 odd nonprimes congruent to 3 mod 4 below 10^n.at n=6A093188
• Semiprimes in A056106.at n=29A113524
• Triangle, read by rows, T(n, k) = f(n,k,q) - f(n,0,q) + 1, where f(n, k, q) = [x^k](p(x,n,q)), p(x, n, q) = (1-x)^(n+1)*Sum_{k >= 0} ( (q*k+1)^n + (q*(k+1)-1)^n )*x^k, and q = 2.at n=23A176198
• Triangle, read by rows, T(n, k) = f(n,k,q) - f(n,0,q) + 1, where f(n, k, q) = [x^k](p(x,n,q)), p(x, n, q) = (1-x)^(n+1)*Sum_{k >= 0} ( (q*k+1)^n + (q*(k+1)-1)^n )*x^k, and q = 2.at n=25A176198
• Conjectured least number k such that prime(n) is the largest divisor of k^3 - 1, or 0 if there is no such k.at n=53A223706
• Number of length 2+2 0..n arrays with the sum of medians of adjacent triples multiplied by some arrangement of +-1 equal to zero.at n=13A253130
• Expansion of Product_{k>=1} (1 + x^k) * (1 + x^(2*k)) * (1 + x^(3*k)) * (1 + x^(4*k)) * (1 + x^(5*k)).at n=31A327047
• Number of ways to tile a 2 X n board with squares and dominoes where vertical dominoes are only allowed in even-numbered locations.at n=10A355327
• Number of ways to tile a hexagonal strip made up of 4*n equilateral triangles, using triangles and diamonds.at n=5A356622
• Array read by antidiagonals: T(n,k) is the number of noncrossing k-gonal cacti with n polygons up to rotation.at n=61A361236
• a(n) is the number of 4 element sets of distinct integer sided strict rectangles that fill an n X n square.at n=35A384724
• Consecutive states of the linear congruential pseudo-random number generator (1255*s + 6173) mod 29282 when started at s=1.at n=26A385339