23920

Appears in sequences

• a(n) = floor(n*(n-1)*(n-2)*(n-3)/15).at n=26A011925
• Nearest integer to Gamma(n + 9/11)/Gamma(9/11).at n=8A020006
• Ceiling of Gamma(n + 9/11)/Gamma(9/11).at n=8A020096
• (Terms in A028286)/2.at n=39A051359
• (Terms in A014450)/2.at n=16A051474
• (Terms in A014450)/2.at n=21A051474
• (Terms in A014472)/2.at n=8A051475
• Number of pentagonal regions in regular n-gon with all diagonals drawn.at n=41A067152
• Number of polyhexes with n cells that tile the plane by translation.at n=13A075207
• Number of binary words of length n that are not "bifix-free".at n=15A094536
• Numbers k such that k + sigma(k) + phi(k) is a square.at n=33A116009
• Icosagonal numbers divisible by 20.at n=11A117798
• Triangle read by rows: numbers of isomers of unbranched a-4-catapolyheptagons.at n=47A120653
• G.f. A(x) satisfies: Series_Reversion( x/A(x) ) / x = 2*A(x) - (1+x).at n=7A120955
• Numbers of isomers of unbranched a-4-catapolyheptagons - see Brunvoll reference for precise definition.at n=7A121139
• Triangle, read by rows, where T(n,k) equals the dot product of the vector of terms in row n that are to the right of T(n,k) with the vector of terms in column k that are above T(n,k) for n>k+1>0, with the odd numbers in the secondary diagonal and all 1's in the main diagonal.at n=38A128320
• Column 2 of triangle A128320.at n=6A128323
• Symmetrical triangle T(n, m) = floor(Eulerian(n+1, m)/2), read by rows.at n=29A174098
• Symmetrical triangle T(n, m) = floor(Eulerian(n+1, m)/2), read by rows.at n=34A174098
• Number of nX3 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,2,0,4,1 for x=0,1,2,3,4.at n=5A196797