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.

A034871 Odd-numbered rows of Pascal's triangle.

Original entry on oeis.org

1, 1, 1, 3, 3, 1, 1, 5, 10, 10, 5, 1, 1, 7, 21, 35, 35, 21, 7, 1, 1, 9, 36, 84, 126, 126, 84, 36, 9, 1, 1, 11, 55, 165, 330, 462, 462, 330, 165, 55, 11, 1, 1, 13, 78, 286, 715, 1287, 1716, 1716, 1287, 715, 286, 78, 13, 1, 1, 15, 105, 455, 1365, 3003, 5005
Offset: 0

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Programs

  • Haskell
    a034871 n = a034871_list !! n
    a034871_list = concat $ map ([1,1] ^) [1,3..]
    instance Num a => Num [a] where
       fromInteger k = [fromInteger k]
       (p:ps) + (q:qs) = p + q : ps + qs
       ps + qs         = ps ++ qs
       (p:ps) * qs'@(q:qs) = p * q : ps * qs' + [p] * qs
        *                = []
    -- Reinhard Zumkeller, Apr 02 2011
  • Mathematica
    Take[Table[Binomial[n,m],{n,0,20},{m,0,n}],{2,-1,2}]//Flatten (* Harvey P. Dale, Dec 10 2018 *)

Formula

G.f.: (1+y)/(1-x*(1+y)^2). - Vladimir Kruchinin, Nov 22 2020