OFFSET
0,1
COMMENTS
a(n) = A077852(n+1) (Barker's recurrence) is correct at least up to n=32000. - R. J. Mathar, Feb 11 2016
Not to be confused with the Pisot T(3,7) sequence, which is A020746. - R. J. Mathar, Feb 13 2016
LINKS
Colin Barker, 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.
FORMULA
Empirical G.f.: -(x^3-x^2+2*x-3) / ((x-1)*(x^3+2*x-1)). [Colin Barker, Dec 21 2012]
a(n+1) = ceiling(a(n)^2/a(n-1))-1 for n>0. - Bruno Berselli, Feb 15 2016
MAPLE
A019489 := proc(n)
option remember;
if n <= 1 then
op(n+1, [3, 7]) ;
else
a := procname(n-1)^2/procname(n-2) ;
if type(a, 'integer') then
a-1 ;
else
floor(a) ;
fi;
end if;
end proc: # R. J. Mathar, Feb 11 2016
PROG
(PARI) T(a0, a1, maxn) = a=vector(maxn); a[1]=a0; a[2]=a1; for(n=3, maxn, a[n]=ceil(a[n-1]^2/a[n-2])-1); a
T(3, 7, 30) \\ Colin Barker, Feb 16 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved