OFFSET
0,1
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
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.
FORMULA
Known not to satisfy any linear recurrence.
There are linear recurrences which match e.g. the first 21 terms, but after a while they always fail. - N. J. A. Sloane, Aug 07 2016
MAPLE
PisotE := proc(a0, a1, n)
option remember;
if n = 0 then
a0 ;
elif n = 1 then
a1;
else
floor( procname(a0, a1, n-1)^2/procname(a0, a1, n-2)+1/2) ;
end if;
end proc:
A014001 := proc(n)
PisotE(7, 15, n) ;
end proc: # R. J. Mathar, Feb 12 2016
MATHEMATICA
a[0] = 7; a[1] = 15;
a[n_] := a[n] = Floor[a[n-1]^2/a[n-2] + 1/2];
a /@ Range[0, 30] (* Jean-François Alcover, Apr 03 2020 *)
PROG
(PARI) pisotE(nmax, a1, a2) = {
a=vector(nmax); a[1]=a1; a[2]=a2;
for(n=3, nmax, a[n] = floor(a[n-1]^2/a[n-2]+1/2));
a
}
pisotE(50, 7, 15) \\ Colin Barker, Jul 27 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Simon Plouffe, Dec 11 1996
STATUS
approved