A179362 - OEIS

%I #10 Dec 01 2012 15:33:34

%S 1,2,6,18,54,162,486,1458,4374,13122,39366,117074,348151,1038313,

%T 3098572,9246640,27592792,82337392,245690824,733114816,2187497080,

%U 6527051536,19475245096,58109645152,173387205336,517354196145,1543686280857

%N Number of permutations of 1..n with i-10<=p(i)<=i+2.

%H R. H. Hardin, <a href="/A179362/b179362.txt">Table of n, a(n) for n = 1..400</a>

%F G.f.: -(-1 + x^2 + 2*x^3 + 4*x^4 + 8*x^5 + 16*x^6 + 30*x^7 + 56*x^8 + 98*x^9 + 140*x^10 + 56*x^11 + 240*x^12 - 26*x^13 - 44*x^14 - 68*x^15 - 82*x^16 - 56*x^17 - 120*x^18 - 22*x^20 - 64*x^21 - 102*x^22 - 40*x^23 - 136*x^24 + 16*x^26 + 40*x^27 + 54*x^28 + 30*x^29 + 68*x^30 + 10*x^33 + 24*x^34 + 6*x^35 + 28*x^36 - 6*x^39 - 12*x^40 - 4*x^41 - 14*x^42 - 2*x^46 - 2*x^48 + x^52 + x^54) / (1 - x - 2*x^2 - 4*x^3 - 8*x^4 - 16*x^5 - 32*x^6 - 62*x^7 - 122*x^8 - 236*x^9 - 440*x^10 - 752*x^11 - 992*x^12 + 57*x^13 + 109*x^14 + 200*x^15 + 340*x^16 + 496*x^17 + 496*x^18 + 52*x^20 + 184*x^21 + 444*x^22 + 784*x^23 + 784*x^24 - 42*x^26 - 138*x^27 - 300*x^28 - 460*x^29 - 392*x^30 - 32*x^33 - 132*x^34 - 276*x^35 - 248*x^36 + 22*x^39 + 82*x^40 + 152*x^41 + 124*x^42 + 12*x^46 + 40*x^47 + 36*x^48 - 7*x^52 - 21*x^53 - 18*x^54 - 2*x^59 - 2*x^60 + x^65 + x^66). - _Vaclav Kotesovec_, Dec 01 2012

%K nonn

%O 1,2

%A _R. H. Hardin_, Jul 11 2010