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!)
A103876 A test for divisibility by the n-th prime p(n). 1
2, 1, 9, 5, 17, 16, 26, 3, 11, 4, 30, 14, 37, 53, 6, 20, 7, 51, 71, 58, 80, 29, 10, 72, 32, 98, 79, 38, 13, 41, 125, 134, 15, 47, 114, 50, 121, 161, 18, 19, 135, 59, 179, 21, 156, 68, 206, 163, 215, 24, 25, 77, 184, 242, 27, 83, 28, 198, 205, 92, 31, 219, 95, 33, 101, 104 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,1

COMMENTS

Delete the last digit from the given number M and subtract a(n) times this deleted digit from the remaining number. If the result is divisible by p(n), M is divisible by p(n). This process may be repeated.

REFERENCES

Alfred S. Posamentier, Math Charmers, Tantalizing Tidbits for the Mind, Prometheus Books, NY, 2003, page 76-81.

LINKS

Table of n, a(n) for n=4..69.

MATHEMATICA

f[n_] := Block[{p = Prime[n], k = 1}, While[ Mod[10k + 1, p] != 0, k++ ]; k]; Table[ f[n], {n, 4, 69}]

CROSSREFS

Cf. A078606.

Sequence in context: A177972 A011136 A067304 * A133174 A155545 A141618

Adjacent sequences:  A103873 A103874 A103875 * A103877 A103878 A103879

KEYWORD

nonn,base

AUTHOR

Alfred S. Posamentier (asp2(AT)juno.com) and Robert G. Wilson v, Feb 10 2005

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 10 01:41 EDT 2020. Contains 336363 sequences. (Running on oeis4.)