21180

Appears in sequences

• Least number beginning with n such that every partial sum is a square.at n=20A095158
• Numbers n such that p(6n) is prime, where p(n) is the number of partitions of n.at n=39A111036
• Triangle read by rows: T(n,k) is the number of binary sequences of length n containing k subsequences 001 (n,k>=0).at n=52A118424
• Number of binary sequences of length n containing exactly one subsequence 001.at n=16A118425
• Rectangular table, read by antidiagonals, such that the g.f. of row n, R_n(y), satisfies: R_n(y) = [ Sum_{k>=0} y^k * R_{n*k}(y) ]^n for n>=0, with R_0(y)=1.at n=50A124550
• Row 4 of table A124550; also equals the self-convolution 4th power of A124564, which is row 4 of table A124560.at n=5A124554
• Numbers n that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (n raised to k+1 must not be a multiple). Case k=12.at n=12A135197
• Numbers k such that Bernoulli number B_{k} has denominator 56786730.at n=2A295598
• a(n) is the total surface area of a hollow cubic block (defined as a block with a shell thickness of 1 cube) where n is the edge length of the removed volume.at n=40A309842
• G.f.: (1 + x) * (1 + x^2) * (1 + x^3) * Product_{k>=1} (1 + x^k).at n=50A329384
• Number of ways to choose 3 points that form an equilateral triangle from the A000292(n) points in a regular tetrahedral grid of side length n.at n=13A334581