23530

Appears in sequences

• Number of singular 2 X 2 matrices over Z(n) (i.e., with determinant = 0).at n=25A020478
• When expressed in base 2 and then interpreted in base 7, is a multiple of the original number.at n=37A062848
• Trajectory of 3 under map n->7n-1 if n odd, n->n/2 if n even.at n=25A063871
• Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=12A207449
• Number of n X 6 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=4A207451
• T(n,k) = Number of n X k 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=49A207453
• Number of 5 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=5A207456
• Number of Sidon subsets of {1,...,n} of size 4.at n=30A241688
• Regular triangle where T(n,k) is the number of inequivalent colorings of free pure symmetric multifunctions (with empty expressions allowed) with n positions and k leaves.at n=51A304485
• Number of equivalence classes, modulo transposition, of non-symmetric plane partitions of n.at n=19A306098
• Sum over all partitions of n of the GCD of the number of parts and the number of distinct parts.at n=34A339312
• Numbers k such that k^6*2^k + 1 is a prime.at n=15A367287
• a(n) = Sum_{1 <= x_1, x_2 <= n} sigma( n/gcd(x_1, x_2, n) ).at n=25A373129
• Array read by antidiagonals: Place k points in general position on each side of a regular n-gon and join every pair of the k*n boundary points by a chord; T(n,k) (n >= 3, k >= 0) gives the number of edges in the resulting planar graph.at n=30A392282