Is everything part of a sequence?

2009 November 8
tags:
by jd2718

I wonder if there is a sequence n_1, n_2, n_3,... of n_i such that 1, 2, n does not appear in the On-Line Encyclopedia of Integer Sequences…

(Nickh, a math blogger, found the solution to an old problem I posed. Turns out, the answers form a known sequence)

[edited to point to the correct Nick - the puzzler at qbyte.org]

6 Responses leave one →
  1. 2009 November 8

    If you plan to work on this, please note A087774 eliminates all numbers two more than a multiple of 3 (ie, 5, 8, 11,…) from consideration.

  2. 2009 November 8

    I don’t know if there is an interesting sequence with that property, but it certainly is true that for any finite list of numbers there is a polynomial f such that that list is the beginning of the sequence f(0), f(1), f(2), …

  3. 2009 November 8

    So we can write a polynomial such that f(0) = 1, f(1) = 2, f(2) = 87 (eg. f(x) = \frac{85}{2}x^2 + -\frac{83}{2}x + 1),

    but the OnLine Dictionary of Integer Sequences has nothing listed.

    So 87 comes first.

    (and yes, I manually checked 1 – 86. Can’t be the best way…)

  4. 2009 November 9

    Hey, it was me who posted about A078511, not that I’d say that constituted finding a solution to your original problem!

    • 2009 November 9

      Puzzle Nick! not worksheet Nick! I should have figured. He’s a nice guy, too.

      Didn’t I cheat you credit once before? I need to work on that. And I’ll go fix the post.

      In any case, thanks for the Sequence, and thanks for the heads up!

      Jonathan

  5. 2009 November 20

    Kristen Told Me About Your iSte, NICE!,

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