21992

Appears in sequences

• Real part of absolute Gaussian perfect numbers, in order of increasing magnitude.at n=32A102531
• a(n) = Sum_{k <= n/2} binomial(n-2k, 3k+2).at n=20A137358
• Number of ballot sequences of length n with exactly 8 fixed points.at n=17A239119
• Number of compositions of n into parts 1, 6, and 7.at n=35A259278
• Number of (n+1) X (1+1) arrays of permutations of 0..n*2+1 with each element having directed index change -2,0 -1,0 0,-1 or 1,1.at n=30A264622
• Triangle read by rows: T(n,k) is the number of free polyominoes with width n and height 1<=k<=n.at n=13A268371
• The number of steps for a walk on a square spiral numbered board when starting on square 1 and stepping to an unvisited square containing the lowest prime number, where the square is within a block of size (2n+1) X (2n+1) centered on the current square. If no unvisited prime numbered squares exist within the block the walk ends.at n=6A336494
• a(n) = Sum_{k=1..n} (A000330(n) mod k^2).at n=50A344711
• Number of compositions of 5*n-1 into parts 3 and 5.at n=12A369846
• Number of binary words of length n avoiding distance (i+1) between "1" digits if the i-th bit is set in the binary representation of n.at n=30A376091
• a(n) = Sum_{k=0..floor(2*n/3)} binomial(2*k,2*n-3*k).at n=16A392428