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 A010907 Pisot sequence E(4,19), a(n) = floor( a(n-1)^2/a(n-2)+1/2 ). 2
 4, 19, 90, 426, 2016, 9541, 45154, 213697, 1011348, 4786332, 22651920, 107203069, 507352048, 2401107571, 11363544486, 53779407822, 254517831936, 1204537747753, 5700626846950, 26978935702753, 127681216679304, 604267465267128, 2859772009358880, 13534231802298265, 64052459384483260, 303136344428812723, 1434630991482656082, 6789572149788327282 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 REFERENCES Shalosh B. Ekhad, N. J. A. Sloane and Doron Zeilberger, Automated Proof (or Disproof) of Linear Recurrences Satisfied by Pisot Sequences, Preprint, 2016. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 D. W. Boyd, Some integer sequences related to the Pisot sequences, Acta Arithmetica, 34 (1979), 295-305 D. W. Boyd, Linear recurrence relations for some generalized Pisot sequences, Advances in Number Theory ( Kingston ON, 1991) 333-340, Oxford Sci. Publ., Oxford Univ. Press, New York, 1993. S. B. Ekhad, N. J. A. Sloane, D. Zeilberger, Automated proofs (or disproofs) of linear recurrences satisfied by Pisot Sequences, arXiv:1609.05570 [math.NT] (2016) Index entries for linear recurrences with constant coefficients, signature (4, 3, 2, 1). FORMULA Theorem: a(n) = 4 a(n - 1) + 3 a(n - 2) + 2 a(n - 3) + a(n - 4). (Proved using the PtoRv program of Ekhad-Sloane-Zeilberger.) - N. J. A. Sloane, Sep 09 2016 G.f.: -(x^3+2*x^2+3*x+4)/(x^4+2*x^3+3*x^2+4*x-1). [Colin Barker, Nov 29 2012] (This follows from the above recurrence. - N. J. A. Sloane, Sep 09 2016) MATHEMATICA PSE[a_, b_, n_]:=Join[{x=a, y=b}, Table[z=Floor[y^2/x+1/2]; x=y; y=z, {n}]]; A010907=PSE[4, 19, 20] (* Zak Seidov, Mar 24 2011 *) nxt[{a_, b_}]:={b, Floor[b^2/a+1/2]}; Transpose[NestList[nxt, {4, 19}, 20]] [[1]] (* Harvey P. Dale, Mar 13 2016 *) CROSSREFS Cf. A077922. Sequence in context: A256959 A181880 A291016 * A229242 A087449 A004253 Adjacent sequences: A010904 A010905 A010906 * A010908 A010909 A010910 KEYWORD nonn AUTHOR Simon Plouffe STATUS approved

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Last modified December 5 21:07 EST 2023. Contains 367594 sequences. (Running on oeis4.)