# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a020749 Showing 1-1 of 1 %I A020749 #20 Sep 08 2022 08:44:45 %S A020749 5,8,12,18,27,40,59,87,128,188,276,405,594,871,1277,1872,2744,4022, %T A020749 5895,8640,12663,18559,27200,39864,58424,85625,125490,183915,269541, %U A020749 395032,578948,848490,1243523,1822472,2670963,3914487,5736960,8407924,12322412,18059373 %N A020749 Pisot sequence T(5,8), a(n) = floor(a(n-1)^2/a(n-2)). %H A020749 Colin Barker, Table of n, a(n) for n = 0..1000 %F A020749 a(n) = 2*a(n-1) - a(n-2) + a(n-3) - a(n-4) (holds at least up to n = 1000 but is not known to hold in general). %F A020749 Note the warning in A010925 from Pab Ter (pabrlos(AT)yahoo.com), May 23 2004: [A010925] and other examples show that it is essential to reject conjectured generating functions for Pisot sequences until a proof or reference is provided. - _N. J. A. Sloane_, Jul 26 2016 %t A020749 RecurrenceTable[{a[0] == 5, a[1] == 8, a[n] == Floor[a[n - 1]^2/a[n - 2] ]}, a, {n, 0, 40}] (* _Bruno Berselli_, Feb 05 2016 *) %o A020749 (Magma) Txy:=[5,8]; [n le 2 select Txy[n] else Floor(Self(n-1)^2/Self(n-2)): n in [1..40]]; // _Bruno Berselli_, Feb 05 2016 %o A020749 (PARI) pisotT(nmax, a1, a2) = { %o A020749 a=vector(nmax); a[1]=a1; a[2]=a2; %o A020749 for(n=3, nmax, a[n] = floor(a[n-1]^2/a[n-2])); %o A020749 a %o A020749 } %o A020749 pisotT(50, 5, 8) \\ _Colin Barker_, Jul 29 2016 %Y A020749 Subsequence of A020745. %Y A020749 See A008776 for definitions of Pisot sequences. %K A020749 nonn %O A020749 0,1 %A A020749 _David W. Wilson_ # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE