|
%I #6 Sep 03 2022 22:51:13
%S 0,42,0,7676,0,1879040,0,489300384,0,129127695440,0,34175930646380,0,
%T 9050948918328308,0,2397326535775801848,0,634999208667955702740,0,
%U 168198450029830487388264,0,44552431219619052902569084,0
%N Number of permutations of an n X 7 array with each element moving exactly one horizontally or vertically and without 2-loops.
%C Column 7 of A216800.
%H R. H. Hardin, <a href="/A216799/b216799.txt">Table of n, a(n) for n = 1..210</a>
%F Empirical: a(n) = 567*a(n-2) -120178*a(n-4) +13765393*a(n-6) -990066780*a(n-8) +48491990634*a(n-10) -1700436524889*a(n-12) +44139613837223*a(n-14) -868138294952960*a(n-16) +13155428910825628*a(n-18) -155474518995038360*a(n-20) +1445657923554944027*a(n-22) -10640770515808065716*a(n-24) +62235780900370087070*a(n-26) -289748793743203750198*a(n-28) +1073469281138893045876*a(n-30) -3157120155190134617652*a(n-32) +7335560093801386722256*a(n-34) -13361939270615901600944*a(n-36) +18863902560832510398528*a(n-38) -20300073543284335116288*a(n-40) +16250247406671839253504*a(n-42) -9322542476450257133568*a(n-44) +3605527632911325986816*a(n-46) -838344981073030021120*a(n-48) +88164689346167832576*a(n-50).
%e Some solutions for n=4
%e ..1..8..3..4..5..6.13....1..2..3..4.11.12..5....1..8..9..2..3.12..5
%e ..0.15..2..9.10.11.12....0..7..8..9.10.19..6....0.15.10.11..4.19..6
%e ..7.22.17.18.19.20.27...21.14.23.16.25.18.13....7.16.23.18.25.26.13
%e .14.21.16.23.24.25.26...22.15.24.17.26.27.20...14.21.22.17.24.27.20
%Y Cf. A216800.
%K nonn
%O 1,2
%A _R. H. Hardin_, Sep 17 2012
| 