180234

Appears in sequences

• Number of rooted 2-connected loopless 4-regular planar maps with n inner faces.at n=8A099553
• Number of semiprimes among n-th million natural numbers.at n=14A216593
• a(n) = n*(n + 7)*(n + 14)*(n + 21)*(n + 28)/120.at n=17A264449
• Number T(n,k) of matchings of size k in the n X n X n triangular grid; triangle T(n,k), n>=0, 0<=k<=floor(n*(n+1)/4), read by rows.at n=30A288852