cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A002122 a(n) = Sum_{t=0..n} g(t)*g(n-t) where g(t) = A002121(t).

Original entry on oeis.org

1, 0, -2, 2, 3, -4, -1, 8, -1, -10, 9, 16, -18, -12, 42, 4, -58, 40, 82, -88, -54, 188, 18, -248, 151, 354, -338, -260, 760, 120, -1031, 574, 1460, -1324, -1076, 2948, 542, -3962, 2075, 5644, -4868, -4290, 11035, 2418, -14900, 7346, 21300, -17652, -16323, 40442, 9768, -54476, 25675, 78290, -62456
Offset: 0

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Keywords

Comments

Arises in studying the Goldbach conjecture.
The last negative term appears to be a(485). - T. D. Noe, Dec 05 2006

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A002121.

Programs

  • Haskell
    a002122 n = a002122_list !! n
    a002122_list = uncurry conv $ splitAt 1 a002121_list where
       conv xs (z:zs) = sum (zipWith (*) xs $ reverse xs) : conv (z:xs) zs
    -- Reinhard Zumkeller, Mar 21 2014

Formula

G.f.: 1/(1+Sum_{k>0} (-x)^prime(k))^2.

Extensions

Edited by Vladeta Jovovic, Mar 29 2003
Entry revised by N. J. A. Sloane, Dec 04 2006