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A164873 The number of permutations of length n that can be sorted by 5 pop stacks in parallel 0
1, 1, 2, 6, 24, 120, 720, 5038, 40004, 347348, 3165888, 29362568, 272387290, 2509750674, 22933267716, 207994616888, 1875239211676, 16832320088082, 150613964836684, 1344743911906806, 11988640129482008, 106774648037691852, 950340529566921394, 8454752823292244122 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..23.

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

Sequence in context: A177548 A193935 A177534 * A226438 A248839 A052399

Adjacent sequences:  A164870 A164871 A164872 * A164874 A164875 A164876

KEYWORD

nonn,easy

AUTHOR

Vincent Vatter, Aug 29 2009

STATUS

approved

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Last modified October 17 21:16 EDT 2019. Contains 328132 sequences. (Running on oeis4.)