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A021008
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Pisot sequence P(5,11), a(0)=5, a(1)=11, a(n+1) is the nearest integer to a(n)^2/a(n-1).
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2
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5, 11, 24, 52, 113, 246, 536, 1168, 2545, 5545, 12081, 26321, 57346, 124941, 272212, 593075, 1292147, 2815232, 6133614, 13363453, 29115278, 63434160, 138205538, 301111747, 656039443, 1429328995, 3114113637, 6784794668
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OFFSET
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0,1
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LINKS
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FORMULA
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Conjecture: G.f.: (2x^3+x^2-4x+5)/(-x^4+2x^2-3x+1). - Ralf Stephan, May 12 2004
Conjecture: a(0)=5, a(1)=11, a(2)=24, a(3)=52, a(n)=3*a(n-1)-2*a(n-2)+a(n-4). - Harvey P. Dale, May 19 2015
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MATHEMATICA
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nxt[{a_, b_}]:={b, Round[b^2/a]}; Transpose[NestList[nxt, {5, 11}, 30]][[1]] (* Harvey P. Dale, May 19 2015 *)
RecurrenceTable[{a[n] == Ceiling[a[n - 1]^2/a[n - 2] - 1/2], a[0] == 5, a[1] == 11}, a, {n, 0, 27}] (* Michael De Vlieger, Aug 08 2016 *)
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PROG
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(PARI) pisotP(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]-1/2));
a
}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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