-2668

Appears in sequences

• Expansion of tanh(tan(x)*sin(x))/2.at n=4A024239
• McKay-Thompson series of class 22B for Monster.at n=41A058568
• McKay-Thompson series of class 22B for the Monster group with a(0) = -2.at n=41A132320
• a(n) = neg(M(n)), where M(n) is the n X n left circulant matrix with (row 1) = (1,3,5,7, ..., 2n - 1), and neg(M(n)) is the negative part of the determinant of M(n); see A380661.at n=3A384077