180480

Appears in sequences

• Number of essentially different ways of arranging numbers 1 through 2*n around a circle so that the sums of each pair of adjacent numbers are neither all prime nor all composite.at n=4A191798
• Number of 2 X 2 matrices having all terms in {1,...,n} and positive odd determinant.at n=30A211068
• Number of 2 X 2 matrices having all terms in {-n,...,0,..,n} and positive odd determinant.at n=14A211158
• a(n) = 1 + Sum_{k=1..n} binomial(n,k) * sigma(k).at n=13A222115
• Number of nX3 0..3 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..3 introduced in row major order.at n=3A240626
• Number of nX4 0..3 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..3 introduced in row major order.at n=2A240627
• T(n,k)=Number of nXk 0..3 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..3 introduced in row major order.at n=17A240629
• T(n,k)=Number of nXk 0..3 arrays with no element equal to exactly two horizontal and vertical neighbors, with new values 0..3 introduced in row major order.at n=18A240629