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A072856
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Number of permutations satisfying i-4<=p(i)<=i+4, i=1..n (permutations of length n within distance 4).
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87
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1, 1, 2, 6, 24, 120, 504, 1902, 6902, 25231, 95401, 365116, 1396948, 5316192, 20135712, 76227216, 288878956, 1095937420, 4159450913, 15783649241, 59878012558, 227128287882, 861543171080, 3268198646496, 12398132725784, 47033439463906, 178423731589482
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OFFSET
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0,3
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COMMENTS
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a(n) equals the permanent of the n X n matrix with 1's along the nine central diagonals and 0's everywhere else. - John M. Campbell, Jul 09 2011
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (3, 2, -1, -1, 70, 39, -31, -114, -522, -184, 34, 46, 1444, 202, -606, 1204, 198, -804, 542, -26, -2372, -318, 1582, -328, -2018, -222, 810, 184, -706, -14, 204, 70, 14, 28, -22, -11, 47, -8, -11, -1, -4, 1, 1).
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FORMULA
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G.f.: (1 -2*x -3*x^2 -x^3 +4*x^4 -31*x^5 -5*x^6 +32*x^7 -21*x^8 +129*x^9 +94*x^10 -83*x^11 +11*x^12 -192*x^13 -59*x^14 +63*x^15 -16*x^16 +3*x^17 -29*x^18 -46*x^19 -57*x^20 +253*x^21 -28*x^22 -101*x^23 +17*x^24 +104*x^25 -15*x^26 -29*x^27 +10*x^28 -x^29 +x^30 -x^32 -3*x^33 +x^35) / (1 -3*x -2*x^2 +x^3 +x^4 -70*x^5 -39*x^6 +31*x^7 +114*x^8 +522*x^9 +184*x^10 -34*x^11 -46*x^12 -1444*x^13 -202*x^14 +606*x^15 -1204*x^16 -198*x^17 +804*x^18 -542*x^19 +26*x^20 +2372*x^21 +318*x^22 -1582*x^23 +328*x^24 +2018*x^25 +222*x^26 -810*x^27 -184*x^28 +706*x^29 +14*x^30 -204*x^31 -70*x^32 -14*x^33 -28*x^34 +22*x^35 +11*x^36 -47*x^37 +8*x^38 +11*x^39 +x^40 +4*x^41 -x^42 -x^43). - Torleiv Kløve, Jan 13 2009; corrected by Colin Barker, Jul 06 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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a(0)=1 prepended and more terms added by Colin Barker, Jul 06 2013
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STATUS
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approved
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