1,2

R. Smith and V. Vatter, The enumeration of permutations sortable by pop stacks in parallel

G.f.: (1-13*x+63*x^2-148*x^3+177*x^4-98*x^5+18*x^6)/(1-14*x+75*x^2-201*x^3+288*x^4-\ 216*x^5+72*x^6)

Sequence in context: A082631 A097483 A007405 this_sequence A079106 A088713 A135106

Adjacent sequences: A164868 A164869 A164870 this_sequence A164872 A164873 A164874

nonn

Vince Vatter (vatter(AT)gmail.com), Aug 29 2009