31800

Appears in sequences

• Intersection of A108027, A108028, A108029 and A108030.at n=15A108109
• Matrix log of triangle A111835, which shifts columns left and up under matrix 8th power; these terms are the result of multiplying each element in row n and column k by (n-k)!.at n=10A111838
• Column 0 of the matrix logarithm (A111838) of triangle A111835, which shifts columns left and up under matrix 8th power; these terms are the result of multiplying the element in row n by n!.at n=4A111839
• Triangle read by rows: T(n,k) (n >= 1, 1 <= k <= n) = largest permanent of any n X n (0,1) matrix with k 1's in each row and column.at n=59A133644
• The sum of the principal diagonals of an n X n spiral.at n=36A137930
• Sum of the principal diagonals of a 2n X 2n square spiral.at n=18A137931
• Number of two-dimensional three-sided prudent 2n-step returns.at n=4A151720
• Number of ways to place 2 nonattacking knights on an n X n board.at n=15A172132
• Number of (n+1) X 2 0..3 arrays with every 2 X 2 subblock nonsingular.at n=2A183702
• Number of (n+1)X4 0..3 arrays with every 2X2 subblock nonsingular.at n=0A183704
• T(n,k) = Number of (n+1) X (k+1) 0..3 arrays with every 2 X 2 subblock nonsingular.at n=3A183710
• T(n,k) = Number of (n+1) X (k+1) 0..3 arrays with every 2 X 2 subblock nonsingular.at n=5A183710
• Numbers k for which 2*k+7, 4*k+7, 6*k+7, 8*k+7, 10*k+7 and 12*k+7 are primes.at n=8A210505
• Prime sieve of Phi.at n=22A247861
• a(n) = 4*(n+1)*(9*n+4).at n=29A304505
• Triangle read by rows: T(n,k) is the number of labeled weakly graded (ranked) posets with n elements and rank k.at n=25A361951