21150

Appears in sequences

• Convolution of primes with themselves.at n=23A014342
• G.f.: Product_{k>=1} (1 + 2*x^k).at n=36A032302
• Number of equilateral triangles formed out of matches that can be found in a hexagonal chunk of side length n in hexagonal array of matchsticks.at n=18A045949
• Expansion of 1/(1-3*x-x^4).at n=9A052917
• Let Do(n) = A006566(n) = n-th dodecahedral number. Consider all integer triples (i,j,k), j >= k > 0, with Do(i) = Do(j) + Do(k), ordered by increasing i; sequence gives k values.at n=21A053019
• 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=27A109026
• a(n) = 94*n^2.at n=15A174337
• Potential magic constants of a 10 X 10 magic square composed of consecutive primes.at n=28A192087
• Numbers a = b + c where a, b, and c contain the same decimal digits.at n=28A203024
• (8*n^3 + 3*n^2 + n) / 6.at n=24A219054
• Number of length-n 0..2 arrays with no repeated value equal to the previous repeated value.at n=9A269461
• The number of edges inside a pentagon formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.at n=4A329710
• Number of partitions of n such that 3*(least part) <= greatest part.at n=36A363211
• Table read by antidiagonals: Place k equally spaced points on each side of a regular n-gon and join every pair of the n*(k+1) boundary points by a chord; T(n,k) (n >= 3, k >= 0) gives the number of edges in the resulting planar graph.at n=23A367324