21670

Appears in sequences

• Coordination sequence for sigma-CrFe, Position Xf.at n=37A009958
• Binomial (Binomial (n,2), 3) - Binomial (Binomial (n,3), 2).at n=10A093567
• Expansion of (1-x-2x^2+sqrt(1-2x-3x^2))/(2(1-x)(1-2x-3x^2)).at n=10A116409
• Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0.at n=47A128564
• Triangle, read by rows, where T(n,k) equals the number of permutations of {1..n+1} with [(nk+k)/2] inversions for n>=k>=0.at n=52A128564
• Number of permutations of {1..n} with n inversions.at n=10A128566
• Derived from the centered polygonal numbers: start with the first triangular number, then the sum of the first square number and the second triangular number, then the sum of first pentagonal number, the second square number and the third triangular number, and so on and so on...at n=24A141534
• Number of reduced words of length n in the Weyl group A_9.at n=10A161457
• Number of reduced words of length n in the Weyl group A_9.at n=35A161457
• First occurrence of n consecutive n's in the decimal expansion of the Copeland-Erdos constant.at n=3A224897