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.

A029885 Boustrophedon transform of 1 followed by Thue-Morse sequence A001285.

Original entry on oeis.org

1, 2, 5, 13, 34, 108, 415, 1841, 9381, 53733, 342086, 2395481, 18300250, 151453434, 1349856656, 12890177378, 131298281746, 1420980348324, 16283235530691, 196958363484995, 2507751773736087, 33526171616091612
Offset: 0

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Programs

  • Haskell
    a029885 n = sum $ zipWith (*) (a109449_row n) (1 : map fromIntegral a001285_list)
    -- Reinhard Zumkeller, Nov 04 2013
  • Mathematica
    tm[n_] := Mod[Sum[Mod[Binomial[n, k], 2], {k, 0, n}], 3];
    T[n_, k_] := (n!/k!) SeriesCoefficient[(1 + Sin[x])/Cos[x], {x, 0, n - k}];
    a[n_] := Sum[T[n, k] If[k == 0, 1, tm[k - 1]], {k, 0, n}];
    Table[a[n], {n, 0, 21}] (* Jean-François Alcover, Jul 02 2019 *)

Extensions

Definition corrected by Reinhard Zumkeller, Nov 04 2013