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!)
A071793 Decimal expansion of the fifth (of 10) decimal selvage number; the n-th digit of a decimal selvage number, x, is equal to the tenths digit of n*x. 5
4, 9, 4, 9, 4, 9, 4, 9, 4, 9, 4, 9, 4, 9, 4, 9, 4, 9, 4, 8, 3, 8, 3, 8, 3, 8, 3, 8, 3, 8, 3, 8, 3, 8, 3, 8, 3, 8, 3, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 7, 2, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 6, 1, 5, 0, 5, 0, 5, 0, 5, 0, 5, 0, 5, 0, 5, 0, 5, 0, 5, 0, 5, 9, 4 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

In other words, this constant satisfies x = Sum_{n>=0} ( floor(10*n*x) (mod 10) ) / 10^n.

LINKS

Table of n, a(n) for n=0..99.

FORMULA

a(n) = floor(10*n*x) (mod 10), where x = Sum_{k>0} a(k)/10^k.

a(n) = 9 - A071873(n).

EXAMPLE

x = .49494949494949494948383838383838383838372727272727...

a(5) = 4 since floor(10*5*x) (mod 10) = 4.

The multiples of this constant x begin:

1*x = 0.4949494949494949494838383838383838383837...

2*x = 0.9898989898989898989676767676767676767675...

3*x = 1.484848484848484848451515151515151515151...

4*x = 1.979797979797979797935353535353535353535...

5*x = 2.474747474747474747419191919191919191919...

6*x = 2.969696969696969696903030303030303030302...

7*x = 3.464646464646464646386868686868686868686...

8*x = 3.959595959595959595870707070707070707070...

9*x = 4.454545454545454545354545454545454545454...

10*x = 4.949494949494949494838383838383838383837...

11*x = 5.444444444444444444322222222222222222221...

12*x = 5.939393939393939393806060606060606060605...

wherein the tenths place of n*x yields the n-th digit of x.

MATHEMATICA

k = 4; f[x_] := Floor[10*FractionalPart[x]]; Clear[xx]; xx[n_] := xx[n] = Catch[For[x = xx[n - 1], True, x += 10^(-n), If[f[n*x] == f[10^(n - 1)*x], Throw[x]]]]; xx[1] = k/10; Scan[xx, Range[100]]; RealDigits[xx[100]][[1]] (* Jean-Fran├žois Alcover, Dec 06 2012 *)

Clear[a]; a[1] = 4; a[2] = 9; a[n0 = 3] = 4; a[_] = 0; digits = 10^(n0-1); Do[a[n] = Mod[Floor[10*n*Sum[a[k]/10^k, {k, 1, n}]], 10], {n, n0+1, digits}]; Table[a[n], {n, 1, digits}]

CROSSREFS

Cf. A071789, A071790, A071791, A071792, A071873, A071874, A071875, A071876, A071877.

Sequence in context: A021673 A224299 A141653 * A010714 A284018 A089090

Adjacent sequences:  A071790 A071791 A071792 * A071794 A071795 A071796

KEYWORD

nonn,cons,base,nice

AUTHOR

Paul D. Hanna, Jun 06 2002

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 5 15:11 EST 2019. Contains 329753 sequences. (Running on oeis4.)