OFFSET
0,3
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
R. Smith and V. Vatter, The enumeration of permutations sortable by pop stacks in parallel
Index entries for linear recurrences with constant coefficients, signature (14,-75,201,-288,216,-72).
FORMULA
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).
a(n) = 14*a(n-1) - 75*a(n-2) + 201*a(n-3) - 288*a(n-4) + 216*a(n-5) - 72*a(n-6) for n>6. - Colin Barker, Jul 02 2019
MATHEMATICA
LinearRecurrence[{14, -75, 201, -288, 216, -72}, {1, 1, 2, 6, 24, 118, 644}, 30] (* Harvey P. Dale, Mar 09 2022 *)
PROG
(PARI) Vec((1 - x)*(1 - 12*x + 51*x^2 - 97*x^3 + 80*x^4 - 18*x^5) / ((1 - 2*x)*(1 - 12*x + 51*x^2 - 99*x^3 + 90*x^4 - 36*x^5)) + O(x^30)) \\ Colin Barker, Jul 02 2019
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincent Vatter, Aug 29 2009
STATUS
approved