1,2

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

G.f.: (1584*x^11-14016*x^10+45432*x^9-79454*x^8+86562*x^7-62624*x^6+30887*x^5-10411* x^4+2352*x^3-339*x^2+28*x-1)/(7920*x^11-40116*x^10+96324*x^9-139728*x^8+133468 *x^7-87278*x^6+39670*x^5-12495*x^4+2666*x^3-366*x^2+29*x-1)

Sequence in context: A152347 A068200 A121987 this_sequence A052398 A047890 A071088

Adjacent sequences: A164869 A164870 A164871 this_sequence A164873 A164874 A164875

nonn

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