25728

Appears in sequences

• Number of permutations of (1,...,n) having n-6 inversions (n>=6).at n=7A005284
• Number of fair sudoku problems with n given values on a 4 x 4 grid.at n=4A109252
• Smaller member of an infinitary amicable pair.at n=9A126169
• Infinitary amicable numbers.at n=18A127664
• Number of reduced words of length n in the Weyl group A_12.at n=7A161461
• Numbers with prime signature {7,1,1}, i.e., of form p^7*q*r with p, q and r distinct primes.at n=33A179696
• Number of ways to place 2 nonattacking nightriders on an n X n toroidal board.at n=15A196812
• Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 1 (constant-stress 1 X 1 tilings).at n=2A234327
• Number of (n+1) X (3+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 1 (constant-stress 1 X 1 tilings).at n=1A234328
• T(n,k) is the number of (n+1) X (k+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 1 (constant-stress 1 X 1 tilings).at n=7A234333
• T(n,k) is the number of (n+1) X (k+1) 0..3 arrays with every 2 X 2 subblock having its diagonal sum differing from its antidiagonal sum by 1 (constant-stress 1 X 1 tilings).at n=8A234333
• Mahonian numbers T(n,7) (cf. A008302).at n=8A242657
• Number of length n+4 0..3 arrays with no disjoint pairs in any consecutive five terms having the same sum.at n=19A247399
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 525", based on the 5-celled von Neumann neighborhood.at n=29A272740
• Totients t such that the number of divisors of t equals the number of solutions of phi(x) = t.at n=23A305058
• E.g.f. C(x,y) = 1 + Integral S(x,y)*C(y,x) dx such that C(x,y)^2 - S(x,y)^2 = 1 and C(y,x) = Integral S(y,x)*C(x,y) dy, where C(x,y) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(2*n-2*k)*y^(2*k)/((2*n-2*k)!*(2*k)!), as a triangle of coefficients T(n,k) read by rows.at n=25A322221
• E.g.f. C(y,x) = 1 + Integral S(y,x)*C(x,y) dy such that C(y,x)^2 - S(y,x)^2 = 1 and C(x,y) = Integral S(x,y)*C(y,x) dx, where C(y,x) = Sum_{n>=0} Sum_{k=0..n} T(n,k) * x^(2*n-2*k)*y^(2*k)/((2*n-2*k)!*(2*k)!), as a triangle of coefficients T(n,k) read by rows.at n=23A322222
• E.g.f. C(x,y) = 1 - Integral S(x,y)*C(y,x) dx such that C(x,y)^2 + S(x,y)^2 = 1 and S(y,x) = Integral C(y,x)*C(x,y) dy, as a triangle of coefficients T(n,k) read by rows.at n=25A367381
• a(n) = Sum_{k=0..floor(n/3)} 2^k * binomial(k,n-3*k)^2.at n=21A387477