0,4

Table 1 of Kim and Kim. Is it pure coincidence that this is so similar to A079494 and is a subsequence of A003178?

Dongsu Kim, Jang Soo Kim, A combinatorial approach to the power of 2 in the number of involutions, Feb 25, 2009.

Sequence in context: A000673 A129383 A052957 this_sequence A074933 A003178 A079494

Adjacent sequences: A157250 A157251 A157252 this_sequence A157254 A157255 A157256

nonn

Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 25 2009