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!)
A261896 Consider the 2^n values of A162795(i)/i^2 for 2^n <= i < 2^(n+1); a(n) = value of i where this quantity is minimized. 1
3, 5, 11, 25, 43, 89, 179, 361, 727, 1459, 2921, 5843, 11689, 23383, 46769, 93543, 187093, 374193, 748391, 1496785, 2993575, 5987157, 11974321, 23948647, 47897299, 95794607, 191589221, 383178449, 766356903, 1532713827, 3065427663, 6130855333, 12261710675, 24523421357, 49046842723 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Sequence suggested by Omar E. Pol.

Note that all values in this sequence are odd and that a(n) is approximately 2*a(n-1).

REFERENCES

D. Applegate, O. E. Pol and N. J. A. Sloane, The toothpick sequence and other sequences from cellular automata, Congressus Numerantium, v. 206 (2010) 157-191.

LINKS

Table of n, a(n) for n=0..34.

D. Applegate, O. E. Pol and N. J. A. Sloane, The toothpick sequence and other sequences from cellular automata; also available at arXiv:1004.3036v2, [math.CO], 2010.

Steven R. Finch, Toothpicks and Live Cells, July 21, 2015. [Cached copy, with permission of the author]

N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS

MATHEMATICA

T = 1; t[0] = 0; t[1] = 1; lst = {1};

Do[twon = 2^n; Tmin = 1; imin = 1;

    Do[If[i==twon, t[i]=twon,

                   t[i]=2*t[i-twon]+t[i-twon+1];

                   If[OddQ[i], T=T+t[i];

                               Ttest=T/(i*i)];

                               If[Ttest<Tmin, Tmin=Ttest; imin=i ]],

      {i, twon, 2*twon - 1}];

    AppendTo[lst, imin],

    {n, 1, 15}];

lst

N[Tmin, 10]

CROSSREFS

Cf. A139250, A147562, A162795, A170927, A195853, A260239, A261313, A261895.

Sequence in context: A018116 A259643 A167796 * A285184 A018008 A104545

Adjacent sequences:  A261893 A261894 A261895 * A261897 A261898 A261899

KEYWORD

nonn

AUTHOR

Robert Price, Sep 05 2015

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 November 29 03:58 EST 2021. Contains 349416 sequences. (Running on oeis4.)