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 1-7 of 7 results.

A027418 Duplicate of A035508.

Original entry on oeis.org

0, 2, 7, 20, 54, 143, 376, 986, 2583, 6764, 17710, 46367, 121392, 317810
Offset: 1

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Author

Keywords

Crossrefs

Bisection of A000071 and A007492. Pairwise sums of A059840.

A333599 a(n) = Fibonacci(n) * Fibonacci(n+1) mod Fibonacci(n+2).

Original entry on oeis.org

0, 1, 2, 1, 7, 1, 20, 1, 54, 1, 143, 1, 376, 1, 986, 1, 2583, 1, 6764, 1, 17710, 1, 46367, 1, 121392, 1, 317810, 1, 832039, 1, 2178308, 1, 5702886, 1, 14930351, 1, 39088168, 1, 102334154, 1, 267914295, 1, 701408732, 1, 1836311902, 1, 4807526975, 1, 12586269024
Offset: 0

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Author

Adnan Baysal, Mar 28 2020

Keywords

Examples

			a(0) = 0*1 mod 1 = 0;
a(1) = 1*1 mod 2 = 1;
a(2) = 1*2 mod 3 = 2;
a(3) = 2*3 mod 5 = 1;
a(4) = 3*5 mod 8 = 7.
		

Crossrefs

Equals A035508 interleaved with A000012.

Programs

  • Mathematica
    With[{f = Fibonacci}, Table[Mod[f[n] * f[n+1], f[n+2]], {n, 0, 50}]] (* Amiram Eldar, Mar 28 2020 *)
  • PARI
    a(n) = if (n % 2, 1, fibonacci(n+2) - 1); \\ Michel Marcus, Mar 29 2020
    
  • PARI
    concat(0, Vec(x*(1 + 3*x - x^3) / ((1 + x)*(1 + x - x^2)*(1 - x - x^2)) + O(x^45))) \\ Colin Barker, Mar 29 2020
  • Python
    def a(n):
        f1 = 0
        f2 = 1
        for i in range(n):
            f = f1 + f2
            f1 = f2
            f2 = f
        return (f1 * f2) % (f1 + f2)
    

Formula

a(2n+1) = 1, and a(2n) = F(2n+2) - 1, and lim(a(2n+2)/a(2n)) = phi^2 by d'Ocagne's identity.
a(n) = F(n) * F(n+1) mod (F(n) + F(n+1)) since F(n+2) := F(n+1) + F(n).
From Colin Barker, Mar 28 2020: (Start)
G.f.: x*(1 + 3*x - x^3) / ((1 + x)*(1 + x - x^2)*(1 - x - x^2)).
a(n) = -a(n-1) + 3*a(n-2) + 3*a(n-3) - a(n-4) - a(n-5) for n>4.
(End)

A152891 a(1) = b(1) = 0; for n > 1, b(n) = b(n-1) + n-1 + a(n-1) and a(n) = a(n-1) + n-1 + b(n).

Original entry on oeis.org

0, 2, 9, 29, 83, 226, 602, 1588, 4171, 10935, 28645, 75012, 196404, 514214, 1346253, 3524561, 9227447, 24157798, 63245966, 165580120, 433494415, 1134903147, 2971215049, 7778742024, 20365011048, 53316291146, 139583862417
Offset: 1

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Author

Keywords

Comments

Partial sums of A035508. - R. J. Mathar, Dec 15 2008

Crossrefs

Cf. A000045, A001906, A035508, A054452 (b sequence).

Programs

  • Maple
    with(combinat): seq(fibonacci(2*n+1)-n-1, n = 1 .. 27); # Emeric Deutsch, Jun 01 2009
  • Mathematica
    lst={};a=b=0;Do[b+=n+a;a+=n+b;AppendTo[lst,a],{n,0,2*4!}];lst
    Table[Fibonacci[2n+1]-n-1,{n,30}] (* or *) LinearRecurrence[{5,-8,5,-1},{0,2,9,29},30] (* Harvey P. Dale, Sep 24 2013 *)

Formula

From R. J. Mathar, Dec 15 2008: (Start)
G.f.: x^2*(2 - x)/((1 - 3*x + x^2)*(1 - x)^2).
a(n) = A001906(n+1) - A001906(n) - n - 1. (End)
a(n) = Fibonacci(2*n+1) - n - 1. - Emeric Deutsch, Jun 01 2009

Extensions

Name corrected by Jon E. Schoenfield, Feb 19 2019

A165279 Table read by antidiagonals: T(n, k) is the k-th number with n-1 odd-indexed Fibonacci numbers in its Zeckendorf representation.

Original entry on oeis.org

1, 3, 2, 4, 5, 7, 8, 6, 15, 20, 9, 10, 18, 41, 54, 11, 13, 19, 49, 109, 143, 12, 14, 28, 52, 130, 287, 376, 21, 16, 36, 53, 138, 342, 753, 986, 22, 17, 39, 75, 141, 363, 897, 1973, 2583, 24, 23, 40, 96, 142, 371, 952, 2350, 5167, 6764, 25, 26, 44, 104, 198, 374
Offset: 1

Views

Author

Clark Kimberling, Sep 13 2009

Keywords

Comments

For n>=0, row n is the monotonic sequence of positive integers m such that the number of odd-indexed Fibonacci numbers in the Zeckendorf representation of m is n.
We begin the indexing at 2; that is, 1=F(2), 2=F(3), 3=F(4), 5=F(5),...
Every positive integer occurs exactly once in the array, so that as a sequence it is a permutation of the positive integers.
For counts of even-indexed Fibonacci numbers, see A165278.
Essentially, (row 0)=A054204, (column 1)=A035508.

Examples

			Northwest corner:
1....3....4....8....9...11...12...21...22...
2....5....6...10...13...14...16...17...23...
7...15...18...19...28...36...39...40...44...
20..41...49...52...53...75...96..104..107...
Examples:
12=8+3+1=F(6)+F(4)+F(2), zero odds, so 12 is in row 0.
28=21+5+2=F(8)+F(5)+F(3), two odds, so 28 is in row 2.
		

Crossrefs

Programs

  • Mathematica
    f[n_] := Module[{i = Ceiling[Log[GoldenRatio, Sqrt[5]*n]], v = {}, m = n}, While[i > 1, If[Fibonacci[i] <= m, AppendTo[v, 1]; m -= Fibonacci[i], If[v != {}, AppendTo[v, 0]]]; i--]; Total[Reverse[v][[1 ;; -1 ;; 2]]]]; T = GatherBy[SortBy[ Range[10^4], f], f]; Table[Table[T[[n - k + 1, k]], {k, n, 1, -1}], {n, 1, Length[T]}] // Flatten (* Amiram Eldar, Feb 04 2020 *)

Extensions

More terms from Amiram Eldar, Feb 04 2020

A210619 Triangle of numbers with n 1's and n 0's in their representation in base of Fibonacci numbers (A014417).

Original entry on oeis.org

2, 6, 7, 17, 19, 20, 46, 51, 53, 54, 122, 135, 140, 142, 143, 321, 355, 368, 373, 375, 376, 842, 931, 965, 978, 983, 985, 986, 2206, 2439, 2528, 2562, 2575, 2580, 2582, 2583, 5777, 6387, 6620, 6709, 6743, 6756, 6761, 6763, 6764, 15126, 16723, 17333, 17566, 17655, 17689, 17702, 17707, 17709, 17710
Offset: 1

Views

Author

Alex Ratushnyak, May 07 2012

Keywords

Comments

There are n such 2n-bit numbers. For example, 17, 19, and 20 all require six bits: 100101, 101001, 101010. The least number in each group is Fib(2n+1) + Fib(2n-1) - 1, which is A005592(n). The greatest number in each group is Fib(2n+2) - 1, which is A035508(n). - T. D. Noe, May 08 2012

Examples

			Representation of 20 is 101010, three 1's and three 0's, so 20 is in the sequence.
Representation of 22 is 1000001, two 1's and five 0's, so 22 is not in the sequence.
		

Crossrefs

Cf. A014417, A003714, A000045 (Fibonacci numbers).
Cf. A005592 (column k=1), A035508 (main diagonal), A249450 (second diagonal), A346434 (in Fibonacci base).

Programs

  • Mathematica
    nn = 10; f = Join[{0}, Accumulate[Fibonacci[Range[2, 2*nn, 2] - 1]]]; t = Table[hi = f[[n+1]] - 1; Reverse[Table[hi - f[[i]], {i, n - 1}]], {n, 2, nn}]; t = Flatten[t] (* T. D. Noe, May 08 2012 *)

Formula

Numbers with equal counts of 1's and 0's in their Zeckendorf representation.
From Kevin Ryde, Jul 24 2021: (Start)
T(n,k) = Fibonacci(2*n+2) - Fibonacci(2*(n-k)) - 1.
G.f.: x*y*(2 - 2*x + x^2 - (1 + x + x^2)*x*y + x^3*y^2) / ( (1-x) * (1 - 3*x + x^2) * (1 - x*y) * (1 - 3*x*y + (x*y)^2) ).
(End)

A364007 Numbers k such that k and k+1 are both Wythoff-Niven numbers (A364006).

Original entry on oeis.org

3, 6, 7, 20, 39, 51, 54, 55, 90, 135, 143, 294, 305, 321, 356, 365, 369, 374, 375, 376, 784, 800, 924, 978, 979, 980, 986, 1904, 1945, 1970, 2043, 2199, 2232, 2289, 2394, 2424, 2439, 2499, 2525, 2562, 2580, 2583, 4185, 4598, 4707, 4774, 4790, 4796, 4879, 5004
Offset: 1

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Author

Amiram Eldar, Jul 01 2023

Keywords

Comments

A035508(n) = Fibonacci(2*n+2) - 1 is a term for n >= 2 since A135818(Fibonacci(2*n+2) - 1) = A135818(Fibonacci(2*n+2)) = 1.

Crossrefs

Programs

  • Mathematica
    seq[count_, nConsec_] := Module[{cn = wnQ /@ Range[nConsec], s = {}, c = 0, k = nConsec + 1}, While[c < count, If[And @@ cn, c++; AppendTo[s, k - nConsec]]; cn = Join[Rest[cn], {wnQ[k]}]; k++]; s]; seq[50, 2] (* using the function wnQ[n] from A364006 *)

A371592 Irregular table T(n, k), n >= 0, k = 1..2^n, read by rows; the n-th row lists the nonnegative integers whose dual Zeckendorf-binary representation has n ones.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 7, 6, 8, 9, 10, 12, 13, 15, 20, 11, 14, 16, 17, 18, 21, 22, 23, 25, 26, 28, 33, 34, 36, 41, 54, 19, 24, 27, 29, 30, 31, 35, 37, 38, 39, 42, 43, 44, 46, 47, 49, 55, 56, 57, 59, 60, 62, 67, 68, 70, 75, 88, 89, 91, 96, 109, 143
Offset: 0

Views

Author

Rémy Sigrist, Mar 28 2024

Keywords

Comments

As a flat sequence, this is a permutation of the nonnegative integers with inverse A371593.

Examples

			Table T(n, k) begins:
    0
    1, 2
    3, 4, 5, 7
    6, 8, 9, 10, 12, 13, 15, 20
    11, 14, 16, 17, 18, 21, 22, 23, 25, 26, 28, 33, 34, 36, 41, 54
    ...
		

Crossrefs

See A371590 for a similar sequence.
Cf. A001911, A035508, A112310, A371593 (inverse).

Programs

  • PARI
    \\ See Links section.

Formula

A112310(T(n, k)) = n.
T(n, 1) = A001911(n).
T(n, 2^n) = A035508(n).
Showing 1-7 of 7 results.