login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A018907 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(2,7). 1
2, 7, 25, 90, 325, 1174, 4241, 15321, 55349, 199956, 722370, 2609667, 9427803, 34059315, 123044249, 444515318, 1605876501, 5801463374, 20958633656, 75716124779, 273535557978, 988187148996, 3569970385786, 12897039359739, 46592438107869, 168321986797406 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
LINKS
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, [2, 7][n+1],
1 +floor(a(n-1)^2/a(n-2)))
end:
seq(a(n), n=0..40); # Alois P. Heinz, May 05 2014
MATHEMATICA
a[n_] := a[n] = Switch[n, 0, 2, 1, 7, _, 1 + Floor[a[n-1]^2/a[n-2]]];
a /@ Range[0, 40] (* Jean-François Alcover, Nov 16 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(2, 7, 40) \\ Colin Barker, Feb 16 2016
CROSSREFS
Sequence in context: A007484 A070859 A048576 * A052936 A108152 A024482
KEYWORD
nonn
AUTHOR
R. K. Guy, Dec 11 1996
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)