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.

Showing 1-4 of 4 results.

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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Author

Keywords

Crossrefs

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

A230951 Boustrophedon transform of Thue-Morse sequence A010059.

Original entry on oeis.org

1, 1, 1, 3, 9, 27, 108, 475, 2421, 13859, 88254, 617957, 4720980, 39070669, 348225424, 3325303894, 33871280413, 366573108019, 4200618576106, 50809739256049, 646929695900154, 8648812936664311, 121132117170628444, 1773647319453218254, 27099334868109293640
Offset: 0

Views

Author

Reinhard Zumkeller, Nov 03 2013

Keywords

Crossrefs

Programs

  • Haskell
    a230951 n = sum $ zipWith (*) (a109449_row n) $ map fromIntegral a010059_list
    
  • Python
    from itertools import count, islice, accumulate
    def A230951_gen(): # generator of terms
        blist = tuple()
        for i in count(0):
            yield (blist := tuple(accumulate(reversed(blist), initial=i.bit_count()&1^1)))[-1]
    A230951_list = list(islice(A230951_gen(),30)) # Chai Wah Wu, Apr 17 2023

Formula

a(n) = Sum_{k=0..n} A109449(n,k)*A010059(k).

A230952 Boustrophedon transform of Hamming weight (A000120).

Original entry on oeis.org

0, 1, 3, 8, 23, 72, 280, 1242, 6331, 36236, 230726, 1615584, 12342422, 102145644, 910393530, 8693609421, 88552405435, 958361506524, 10982014291650, 132835979792636, 1691320230842116, 22611285878526978, 316685416851528722, 4636988553066906265
Offset: 0

Views

Author

Reinhard Zumkeller, Nov 03 2013

Keywords

Crossrefs

Programs

  • Haskell
    a230952 n = sum $ zipWith (*) (a109449_row n) $ map fromIntegral a000120_list
    (Python 3.10+)
    from itertools import accumulate, count, islice
    def A230952_gen(): # generator of terms
            blist = tuple()
            for i in count(0):
                yield (blist := tuple(accumulate(reversed(blist),initial=i.bit_count())))[-1]
    A230952_list = list(islice(A230952_gen(),40)) # Chai Wah Wu, Jun 12 2022
  • Mathematica
    T[n_, k_] := (n!/k!) SeriesCoefficient[(1 + Sin[x])/Cos[x], {x, 0, n - k}];
    a[n_] := Sum[T[n, k] DigitCount[k, 2, 1], {k, 0, n}];
    Table[a[n], {n, 0, 23}] (* Jean-François Alcover, Jul 23 2019 *)

Formula

a(n) = Sum_{k=0..n} A109449(n,k)*A000120(k).

A230958 Boustrophedon transform of Thue-Morse sequence A001285.

Original entry on oeis.org

1, 3, 7, 15, 39, 127, 480, 2143, 10907, 62495, 397814, 2785861, 21282228, 176133285, 1569817724, 14990658724, 152693582275, 1652531857935, 18936620009722, 229053108410969, 2916394751599614, 38989325834726043, 546070266163669664, 7995699956778626764
Offset: 0

Views

Author

Reinhard Zumkeller, Nov 04 2013

Keywords

Crossrefs

Programs

  • Haskell
    a230958 n = sum $ zipWith (*) (a109449_row n) $ map fromIntegral a001285_list
    
  • Mathematica
    T[n_, k_] := (n!/k!) SeriesCoefficient[(1 + Sin[x])/Cos[x], {x, 0, n - k}];
    tm[n_] := Mod[Sum[Mod[Binomial[n, k], 2], {k, 0, n}], 3];
    Table[Sum[T[n, k] tm[k], {k, 0, n}], {n, 0, 23}] (* Jean-François Alcover, Jul 23 2019 *)
  • Python
    from itertools import accumulate, count, islice
    def A230958_gen(): # generator of terms
        blist = tuple()
        for i in count(0):
            yield (blist := tuple(accumulate(reversed(blist), initial=2 if i.bit_count()&1 else 1)))[-1]
    A230958_list = list(islice(A230958_gen(),30)) # Chai Wah Wu, Apr 17 2023

Formula

a(n) = Sum_{k=0..n} A109449(n,k)*A001285(k).
Showing 1-4 of 4 results.