Jump to content

Undulating number

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by ZeroOne (talk | contribs) at 01:50, 12 March 2006 (Category:Base-dependent integer sequences). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

An undulating number is any number that has the form ababab... when in the base 10 number system.

It is only considered after at least three digits, because otherwise all numbers below 100 would be undulating. The first 20 such numbers are:

101, 111, 121, 131, 141, 151, 161, 171, 181, 191, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292 (sequence A046075 in the OEIS)

Some higher undulating numbers are: 99999, 1717171, 6363, 7777, 80808

Below 10,000 there are exactly 180 undulating numbers.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Undulating_number&oldid=43372753"