OFFSET
0,3
LINKS
R. Smith and V. Vatter, The enumeration of permutations sortable by pop stacks in parallel
FORMULA
G.f.: (-1 -244911168*x^14 +51*x +424049816*x^13 +16848*x^3 -1189*x^2 -162623*x^4 +1135115*x^5 -5933360*x^6 +93180816*x^15 +176551085*x^9 +475936304*x^11 +23718538*x^7 -330046233*x^10 +1620000*x^17 -73376545*x^8 -20032128*x^16 -521745326*x^12)/(9720000*x^17 -68563152*x^16 +235662840*x^15 -511522200*x^14 +774005724*x^13 -859429792*x^12 +721925168*x^11 -467470314*x^10 +235918701*x^9 -93247962*x^8 +28849981*x^7 -6944099*x^6 +1283865*x^5 -178422*x^4 +17989*x^3 -1239*x^2 +52*x -1).
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincent Vatter, Aug 29 2009
STATUS
approved