login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A087720 Repeated terms in the Hofstadter batrachian sequence A005185. 0
1, 3, 5, 6, 8, 11, 12, 14, 16, 17, 23, 24, 30, 32, 43, 47, 48, 54, 60, 72, 80, 83, 84, 92, 94, 96, 148, 172, 175, 178, 185, 186, 192, 215, 222, 228, 230, 252, 273, 301, 308, 338, 350, 372, 380, 382, 384, 408, 468, 517, 574, 593, 624, 673, 678, 738, 748, 762, 764, 789 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Repeating consecutive elements is a characteristic of chaotic sequences.

LINKS

Table of n, a(n) for n=1..60.

FORMULA

a[n] =a[n - a[n-1]] + a[n - a[n-2]]

MATHEMATICA

digits=30000 Hofstadter[n_Integer?Positive] := Hofstadter[n] = Hofstadter[n - Hofstadter[n-1]] + Hofstadter[n - Hofstadter[n-2]] Hofstadter[1] = Hofstadter[2] = 1 a1=Table[Hofstadter[n], {n, 1, digits}]; b=Table[If[a1[[n]]-a1[[n-1]]==0, a1[[n]], 0], {n, 2, digits}]; c=Delete[Union[b], 1]

CROSSREFS

Cf. A005185.

Sequence in context: A014254 A131422 A301744 * A309544 A154111 A047444

Adjacent sequences:  A087717 A087718 A087719 * A087721 A087722 A087723

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Sep 29 2003

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 22 09:32 EDT 2020. Contains 337289 sequences. (Running on oeis4.)