21873

Appears in sequences

• The 5x + 1 sequence beginning at 7.at n=35A028389
• Numbers k such that 10^k - 3 is prime.at n=10A089675
• Number of partitions of n into parts not greater than sqrt(n).at n=52A097356
• 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, 1, 1), (1, 0, -1), (1, 1, 1)}.at n=8A149645
• G.f.: (1+x+x^3+x^5)/( (1-x^2+x^3)*(1-x-x^3) ).at n=25A177485
• Trajectory of 7 under repeated application of the map in A185452.at n=21A185455
• Number of n X 2 0..4 arrays with no element equal to another at a city block distance of exactly two, and new values 0..4 introduced in row major order.at n=5A222940
• T(n,k) = Number of n X k 0..4 arrays with no element equal to another at a city block distance of exactly two, and new values 0..4 introduced in row major order.at n=22A222944
• T(n,k) = Number of n X k 0..4 arrays with no element equal to another at a city block distance of exactly two, and new values 0..4 introduced in row major order.at n=26A222944
• a(n) = sum of all divisors of all positive integers <= prime(n).at n=37A244583
• Number of length 4 0..n arrays with each partial sum starting from the beginning no more than one standard deviation from its mean.at n=15A244792
• 5x + 1 sequence beginning at 11.at n=39A259193
• Number of partitions of positive integer n such that all parts are less than the square root of n.at n=51A316353
• G.f. A(x) satisfies A(x) = 1 + x * A(x)^(3/2) * (1 + A(x)^(3/2)).at n=6A370474