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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A032925 Numbers whose set of base-4 digits is {1,2}. 8
1, 2, 5, 6, 9, 10, 21, 22, 25, 26, 37, 38, 41, 42, 85, 86, 89, 90, 101, 102, 105, 106, 149, 150, 153, 154, 165, 166, 169, 170, 341, 342, 345, 346, 357, 358, 361, 362, 405, 406, 409, 410, 421, 422, 425, 426, 597, 598, 601, 602, 613 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Intersection of A023705 and A023717; A179888 is the intersection of this sequence and A053754. - Reinhard Zumkeller, Jul 31 2010

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..1000

FORMULA

a(2n) = 4a(n-1) + 2, a(2n+1) = 4a(n) + 1. - Ralf Stephan, Oct 07 2003, corrected R. J. Mathar, Sep 07 2016

MAPLE

A032925 := proc(n)

    option remember;

    if n <= 2 then

        n;

    else

        if type(n, 'even') then

            2+4*procname(n/2-1) ;

        else

            1+4*procname(floor(n/2)) ;

        end if;

    end if;

end proc:

seq(A032925(n), n=1..100) ;  # R. J. Mathar, Sep 07 2016

MATHEMATICA

Flatten[Table[FromDigits[#, 4]&/@Tuples[{1, 2}, n], {n, 5}]] (* Vincenzo Librandi, Jun 05 2012 *)

PROG

(MAGMA) [n: n in [1..1000] | Set(IntegerToSequence(n, 4)) subset {1, 2}]; // Vincenzo Librandi, Jun 05 2012

(Haskell)

import Data.List (transpose)

a032925 n = a032925_list !! (n-1)

a032925_list = 1 : 2 : (concat $ transpose [map (+ 1) fs, map (+ 2) fs])

               where fs = map (* 4) a032925_list

-- Reinhard Zumkeller, Apr 18 2015

CROSSREFS

Cf. A023705, A023717, A179888, A053754.

Sequence in context: A078632 A309242 A122701 * A244749 A166087 A333545

Adjacent sequences:  A032922 A032923 A032924 * A032926 A032927 A032928

KEYWORD

nonn,base,easy

AUTHOR

Clark Kimberling

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 December 2 22:46 EST 2021. Contains 349445 sequences. (Running on oeis4.)