login
This site is supported by donations to The OEIS Foundation.

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A309646 Digits of the 10-adic integer (-71/9)^(1/3). 3
1, 6, 3, 1, 6, 7, 2, 5, 4, 5, 8, 8, 0, 7, 7, 0, 9, 9, 6, 5, 4, 1, 8, 9, 2, 8, 3, 5, 3, 4, 6, 9, 6, 8, 4, 3, 0, 2, 6, 7, 5, 7, 5, 7, 9, 3, 7, 7, 9, 7, 6, 3, 2, 1, 5, 3, 4, 8, 4, 2, 4, 9, 0, 5, 5, 9, 0, 4, 4, 8, 0, 9, 7, 5, 2, 2, 3, 3, 5, 9, 8, 9, 3, 7, 0, 3, 1, 6, 0, 2, 0, 3, 9, 7, 6, 5, 3, 1, 3, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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) = 1, b(n) = b(n-1) + 7 * (9 * b(n-1)^3 + 71) mod 10^n for n > 1, then a(n) = (b(n+1) - b(n))/10^n.

EXAMPLE

       1^3 == 1      (mod 10).

      61^3 == 81     (mod 10^2).

     361^3 == 881    (mod 10^3).

    1361^3 == 8881   (mod 10^4).

   61361^3 == 88881  (mod 10^5).

  761361^3 == 888881 (mod 10^6).

PROG

(PARI) N=100; Vecrev(digits(lift(chinese(Mod((-71/9+O(2^N))^(1/3), 2^N), Mod((-71/9+O(5^N))^(1/3), 5^N)))), N)

(Ruby)

def A309646(n)

  ary = [1]

  a = 1

  n.times{|i|

    b = (a + 7 * (9 * a ** 3 + 71)) % (10 ** (i + 2))

    ary << (b - a) / (10 ** (i + 1))

    a = b

  }

  ary

end

p A309646(100)

CROSSREFS

Cf. A309600, A309602.

Sequence in context: A092151 A066717 A176395 * A195494 A154969 A192741

Adjacent sequences:  A309643 A309644 A309645 * A309647 A309648 A309649

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 December 9 00:32 EST 2019. Contains 329871 sequences. (Running on oeis4.)