“What comes next after 1, 2, 4, 9, 20, 48, 115, 286, 719, … ? (for example). This is the place to find out!” and “Most people use this web site to get information about a particular number sequence. If you are a new visitor, then you might ask the database if it can recognize your favorite sequence, if you have one. To do this, go to the main look-up page. (Of course, the number sequence should be well-defined, of general interest and ideally it should be infinite. Short sequences such as phone numbers are not appropriate.)”