cp's OEIS Frontend

A189587 Number of permutations of 1..n with displacements restricted to {-5,-4,-3,-1,0,2}.

%I A189587 #7 Jun 02 2025 04:02:43
%S A189587 1,1,2,4,10,23,48,94,188,389,808,1692,3505,7225,14895,30751,63601,
%T A189587 131549,272040,562259,1161936,2401478,4963797,10260810,21209922,
%U A189587 43841365,90619265,187308371,387166791,800278120,1654186266,3419218303,7067543993
%N A189587 Number of permutations of 1..n with displacements restricted to {-5,-4,-3,-1,0,2}.
%H A189587 R. H. Hardin, <a href="/A189587/b189587.txt">Table of n, a(n) for n = 1..200</a>
%F A189587 Empirical: a(n) = a(n-1) +2*a(n-3) +a(n-4) +5*a(n-5) +4*a(n-6) +9*a(n-7) -2*a(n-8) +5*a(n-9) -6*a(n-10) -2*a(n-11) -3*a(n-12) -5*a(n-13) -2*a(n-14) -3*a(n-15) -a(n-16) +a(n-19) +a(n-20) +a(n-21)
%e A189587 Some solutions for n=11
%e A189587 ..1....2....1....1....1....2....5....2....2....2....4....5....4....1....2....4
%e A189587 ..2....3....3....6....2....5....3....6....3....3....3....3....3....2....3....5
%e A189587 ..4....1....6....3....3....1....1....1....1....1....1....1....1....3....1....1
%e A189587 ..5....5....2....2....4....4....2....4....4....8....2....2....2....4....4....2
%e A189587 ..3....6....5....5....5....3....6....3...10....5...10....6....5....5....5....3
%e A189587 ..6....4....4....4....6....6....4....7....9....4...11....4....9...11....9....7
%e A189587 ..7....7...11...11....7....7...10....5....5...11....5....8....7....7...10....8
%e A189587 ..8....9....8....8....8....8....9....9....6....6....6...11....6....6....6....6
%e A189587 .10...10....7....7....9...10....7...10....7....7....7....7...10...10....7...10
%e A189587 .11....8...10...10...10...11....8....8....8...10....8...10....8....8....8...11
%e A189587 ..9...11....9....9...11....9...11...11...11....9....9....9...11....9...11....9
%K A189587 nonn
%O A189587 1,3
%A A189587 _R. H. Hardin_ Apr 24 2011