Dear all, I don't know how OEIS works, but there must be examples, such as Allan's, where a sequence can, in certain circumstances, begin a term (or two?) earlier than in the context in which it was originally entered. The classical example is the Fibs, which ``properly'' begin 0,1,1,2,3,... but in many contexts appear as 1,1,2,3,... (number of ways of putting dominoes in a 2 by n box, starting at n=0). It would probably not be too difficult to find a ``natural'' occurrence of the sequence 1,0,1,1,2,3,... There should be (probably there is) a way to adjoin terms at the beginning of a sequence. R. PS So as not to make even more of myself than usual, I did a bit of searching, ignoring Neil's excellent advice. A002988, a002955 are almost clasical examples (and I believe related to the Catalan numbers, though it doesn't say so). A013984 may lead me to what I'm looking for: How about the expansion of 1/(1-x^2-x^3-x^4-x^5-x^6-......) ? Bingo! Generating function (1-x)/(1-x-x^2). Not in OEIs, though A039834 is (!) and A005170, A013986, A013987 are close. R. On Sun, 27 May 2012, Neil Sloane wrote:
The instructions for using the OEIS have always said "when looking up a sequence, omit the first couple of terms, since people may have different opinions about where a sequence begins"! Neil
On Wed, May 23, 2012 at 5:06 PM, Allan Wechsler <acwacw@gmail.com> wrote:
@Veit, thank you! It bothers me a little that sticking a completely-mathematically-justified zero on the front of this sequence causes OEIS to miss it entirely.
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