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!)
A309647 Digits of the 10-adic integer (-53/9)^(1/3). 2
7, 2, 6, 1, 3, 2, 9, 4, 6, 9, 1, 4, 6, 5, 1, 8, 6, 9, 0, 9, 6, 7, 0, 7, 6, 3, 6, 7, 5, 6, 4, 8, 4, 7, 0, 1, 9, 2, 3, 9, 6, 0, 0, 5, 7, 4, 6, 9, 6, 7, 9, 6, 7, 1, 7, 1, 2, 1, 6, 8, 9, 9, 5, 3, 5, 8, 1, 0, 5, 1, 4, 6, 4, 6, 2, 6, 8, 3, 2, 0, 8, 8, 1, 4, 9, 7, 4, 2, 3, 6, 1, 0, 5, 7, 2, 6, 9, 6, 3, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

FORMULA

Define the sequence {b(n)} by the recurrence b(0) = 0 and b(1) = 7, b(n) = b(n-1) + 3 * (9 * b(n-1)^3 + 53) mod 10^n for n > 1, then a(n) = (b(n+1) - b(n))/10^n.

EXAMPLE

       7^3 == 3      (mod 10).

      27^3 == 83     (mod 10^2).

     627^3 == 883    (mod 10^3).

    1627^3 == 8883   (mod 10^4).

   31627^3 == 88883  (mod 10^5).

  231627^3 == 888883 (mod 10^6).

PROG

(PARI) N=100; Vecrev(digits(lift(chinese(Mod((-53/9+O(2^N))^(1/3), 2^N), Mod((-53/9+O(5^N))^(1/3), 5^N)))), N)

(Ruby)

def A309647(n)

  ary = [7]

  a = 7

  n.times{|i|

    b = (a + 3 * (9 * a ** 3 + 53)) % (10 ** (i + 2))

    ary << (b - a) / (10 ** (i + 1))

    a = b

  }

  ary

end

p A309647(100)

CROSSREFS

Cf. A309600, A309601.

Sequence in context: A248285 A117029 A128475 * A225444 A175408 A019934

Adjacent sequences:  A309644 A309645 A309646 * A309648 A309649 A309650

KEYWORD

nonn,base

AUTHOR

Seiichi Manyama, Aug 11 2019

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 August 15 01:40 EDT 2020. Contains 336484 sequences. (Running on oeis4.)