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A019482 Define the sequence S(a(0),a(1)) by a(n+2) is the least integer such that a(n+2)/a(n+1) > a(n+1)/a(n) for n >= 0. This is S(4,28). 1
4, 28, 197, 1387, 9766, 68764, 484179, 3409187, 24004668, 169020968, 1190105509, 8379736191, 59003154006, 415451286688, 2925263479867, 20597279875727, 145028966176516, 1021173725712004, 7190258646781909, 50627839422302787, 356479265974341398 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

This coincides with the linearly recurrent sequence defined by the expansion of (4-3*x^2)/(1-7*x-x^2+5*x^3) only up to n<=55. - R. J. Mathar, Feb 10 2016

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

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.

MAPLE

a:= proc(n) option remember;

      `if`(n<2, [4, 28][n+1], floor(a(n-1)^2/a(n-2))+1)

    end:

seq(a(n), n=0..30);  # Alois P. Heinz, Feb 10 2016

MATHEMATICA

a[n_] := a[n] = Switch[n, 0, 4, 1, 28, _, Floor[a[n - 1]^2/a[n - 2]] + 1];

a /@ Range[0, 30] (* Jean-Fran├žois Alcover, Feb 06 2020, after Alois P. Heinz *)

PROG

(PARI) S(a0, a1, maxn) = a=vector(maxn); a[1]=a0; a[2]=a1; for(n=3, maxn, a[n]=a[n-1]^2\a[n-2]+1); a

S(4, 28, 40) \\ Colin Barker, Feb 16 2016

CROSSREFS

Sequence in context: A002903 A208704 A270471 * A198630 A246021 A090965

Adjacent sequences:  A019479 A019480 A019481 * A019483 A019484 A019485

KEYWORD

nonn

AUTHOR

R. K. Guy

STATUS

approved

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Last modified June 5 09:58 EDT 2020. Contains 334840 sequences. (Running on oeis4.)