20818

Appears in sequences

• Diagonal in array of n-gonal numbers A081422.at n=27A081435
• Triangle read by rows: T(n,k) = number of labeled graphs on n nodes with k connected components, 1<=k<=n.at n=23A143543
• Number of n X 3 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,0,4,1,2 for x=0,1,2,3,4.at n=13A196141
• Number of n X 2 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of elements above it, modulo 4.at n=5A239399
• T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of the elements above it, modulo 4.at n=26A239405
• Number of 6Xn 0..3 arrays with no element equal to one plus the sum of elements to its left or two plus the sum of the elements above it, modulo 4.at n=1A239410
• Expansion of Product_{k>=1} 1/(1-x^(k+4))^k.at n=35A263360
• Expansion of -(4*x^3-7*x^2+4*x-1)/(2*x^4-5*x^3+8*x^2-5*x+1).at n=11A271176
• Number of labeled graphs on n nodes with three connected components.at n=6A323876
• Number of binary carry-connected integer partitions of n.at n=39A325098
• a(n) = Sum_{ i=2..n-1, j=1..i-1, gcd(i,j)=1 } (n-i)*(n-j).at n=22A332612