23568

Appears in sequences

• a(n) = a(n-1) + n*a(n-2); a(0) = a(1) = 1.at n=10A000932
• Numbers whose base-5 representation contains exactly three 2's and three 3's.at n=21A045277
• Triangle read by rows where T(n+1,k)=T(n,k)+n*T(n-1,k) starting with T(n,n)=1 and T(n,k)=0 if n<k.at n=67A070895
• Second convolution of A001045(n+1) (generalized (1,2)-Fibonacci), n>=0, with itself.at n=10A073372
• E.g.f. exp(-x)*cosh(x)/(1-x)^2.at n=7A088127
• a(0) = 0, a(1) = 1, a(2) = 1, a(3) = 2, a(4) = 4, for n>3: a(n+1) = SORT[a(n) + a(n-1) + a(n-2) + a(n-3)], where SORT places digits in ascending order and deletes 0's.at n=32A108564
• Numbers k such that k + sigma(k) + phi(k) is a square.at n=32A116009
• The LerchPhi functional part of A060187 MacMahon numbers is treated/ solved for as a curvature to give a set of polynomial triangle sequence coefficients: p(x,n) = Sum[A060187(n,m)*x^(m-1),{m,0,n}]; q(x,n)=k from Solve[FullSimplify[ExpandAll[p[x, n]/(x - 1)^n]] - (1 + k/x^2) == 0, k].at n=18A146543
• Number of partitions of 5n such that cn(1,5) = cn(4,5) and cn(2,5) = cn(3,5).at n=11A202091
• T(n,k)=Number of idempotent n X n 0..k matrices.at n=31A222821
• Number of idempotent 4X4 0..n matrices.at n=4A222823
• Numbers for which the number of prime divisors counted with multiplicity and the sum of the distinct prime divisors are both perfect.at n=15A233563
• Number of (n+1)X(2+1) 0..3 arrays with every 2X2 subblock having the sum of the squares of the edge differences equal to 6.at n=3A233676
• Number of (n+1) X (4+1) 0..3 arrays with every 2 X 2 subblock having the sum of the squares of the edge differences equal to 6.at n=1A233678
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with every 2X2 subblock having the sum of the squares of the edge differences equal to 6 (6 maximizes T(1,1)).at n=11A233682
• T(n,k)=Number of (n+1)X(k+1) 0..3 arrays with every 2X2 subblock having the sum of the squares of the edge differences equal to 6 (6 maximizes T(1,1)).at n=13A233682
• Sums of Pythagorean sextuples in increasing order: The sums of sets of six natural numbers which correspond to the lengths of the edges of a tetrahedron whose four faces are all different Pythagorean triangles.at n=41A248548
• Number of length 3+1 0..2*n arrays with the sum of the absolute values of adjacent differences equal to 3*n.at n=17A249983
• Number of (n+2) X (7+2) 0..3 arrays with every 3 X 3 subblock row and column sum not equal to 0 3 5 6 or 7 and every 3 X 3 diagonal and antidiagonal sum equal to 0 3 5 6 or 7.at n=21A252253
• Number of (7+2) X (n+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=12A252391