18985

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has period 93.at n=15A020432
• Number of partitions of n with equal number of parts congruent to each of 0 and 1 (mod 4).at n=51A035540
• Numerators of continued fraction convergents to sqrt(177).at n=6A041326
• Number of nonisomorphic unrooted Eulerian planar maps with n edges (Eulerian means that all vertices are of even valency; there is an Eulerian cycle).at n=9A069727
• Positive numbers y such that y^2 is of the form x^2+(x+727)^2 with integer x.at n=6A159893
• Partial sums of A049486.at n=30A174655
• Semiprime centered triangular numbers.at n=41A184481
• Number of 2 X 2 matrices with all terms in {0,1,...,n} and even determinant.at n=12A210369
• Number of 2 X 2 matrices having all terms in {-n,...,0,..,n} and even determinant.at n=6A211154
• Expansion of Product_{k>=1} (1 + x^k - x^(3*k)) / (1 - x^k).at n=25A266650
• p-INVERT of (0,1,0,1,0,1,...), where p(S) = 1 - S - S^3.at n=15A291219
• Squarefree semiprimes that are centered triangular numbers.at n=38A380913
• Truncated hex numbers: a(n) = 24*n^2 + 6*n + 1.at n=28A381424