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!)
A030992 7-automorphic numbers ending in 8: final digits of 7n^2 agree with n. 1
8, 68, 768, 2768, 72768, 872768, 3872768, 83872768, 683872768, 1683872768, 11683872768, 11683872768, 11683872768, 20011683872768, 820011683872768, 4820011683872768, 34820011683872768, 534820011683872768 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) is the unique positive integer less than 10^n such that a(n) is divisible by 2^n and 7a(n) - 1 is divisible by 5^n. - Eric M. Schmidt, Aug 18 2012

LINKS

Eric M. Schmidt, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Automorphic Number

Index entries for sequences related to automorphic numbers

Index entries for sequences related to final digits of numbers

PROG

(Sage) [crt(0, inverse_mod(7, 5^n), 2^n, 5^n) for n in range(1, 1001)] # Eric M. Schmidt, Aug 18 2012

CROSSREFS

Sequence in context: A167859 A243246 A113357 * A091590 A303010 A087487

Adjacent sequences:  A030989 A030990 A030991 * A030993 A030994 A030995

KEYWORD

nonn,base,changed

AUTHOR

Eric W. Weisstein

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 15 09:05 EST 2019. Contains 329995 sequences. (Running on oeis4.)