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A048582 Pisot sequence L(4,9). 2
4, 9, 21, 49, 115, 270, 634, 1489, 3498, 8218, 19307, 45359, 106565, 250361, 588192, 1381884, 3246565, 7627402, 17919636, 42099965, 98908653, 232373629, 545933059, 1282602102, 3013314774, 7079409829, 16632196530, 39075285666, 91802543767, 215678705823 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Colin Barker, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = 3*a(n-1) - 2*a(n-2) + a(n-3) + a(n-4) - 2*a(n-5) + a(n-6) - a(n-7) (conjectured). Recurrence is satisfied for at least 760000 terms. - Chai Wah Wu, Jul 25 2016

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

PROG

(PARI) pisotL(nmax, a1, a2) = {

  a=vector(nmax); a[1]=a1; a[2]=a2;

  for(n=3, nmax, a[n] = ceil(a[n-1]^2/a[n-2]));

  a

}

pisotL(50, 4, 9) \\ Colin Barker, Aug 07 2016

CROSSREFS

See A008776 for definitions of Pisot sequences.

Sequence in context: A122498 A132750 A297296 * A069231 A243635 A243636

Adjacent sequences:  A048579 A048580 A048581 * A048583 A048584 A048585

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified October 22 01:42 EDT 2018. Contains 316431 sequences. (Running on oeis4.)