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.

Previous Showing 91-100 of 100 results.

A220469 Fibonacci 14-step numbers, a(n) = a(n-1) + a(n-2) + ... + a(n-14).

Original entry on oeis.org

1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16383, 32765, 65528, 131052, 262096, 524176, 1048320, 2096576, 4193024, 8385792, 16771072, 33541120, 67080192, 134156288, 268304384, 536592385, 1073152005, 2146238482, 4292345912, 8584429728
Offset: 1

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Author

Ruskin Harding, Feb 20 2013

Keywords

Comments

Also called tetradecanacci numbers. In previous similar sequences, a(1),...,a(n-1) have been set equal to zero and a(n)=1. For example, A168084 (Fibonacci 13-step numbers) has 12 0's as the first 12 terms and a(13)=1.

Crossrefs

Cf. A000045 (Fibonacci), A000073 (tribonacci), A000078 (tetranacci), A001591 (pentanacci).

Programs

  • Mathematica
    FibonacciSequence[n_, kMax_] := Module[{a, s}, a = Join[{1}, Table[0, {n - 1}]]; lst = {}; Table[s = Plus @@ a; a = RotateLeft[a]; a[[n]] = s, {k, 1, kMax}]]; FibonacciSequence[14, 50] (* T. D. Noe, Feb 20 2013 *)
    Drop[LinearRecurrence[PadRight[{},14,1],Join[PadRight[{},13,0],{1}],50],13] (* Harvey P. Dale, Feb 25 2013 *)
    LinearRecurrence[{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},{1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096},35] (* Ray Chandler, Aug 03 2015 *)

A298371 a(n) = Sum_{m=0..n} Sum_{i=0..m} i*C(m-i,i)*C(m-i,n-m-i).

Original entry on oeis.org

0, 0, 1, 3, 7, 17, 40, 90, 198, 430, 922, 1956, 4115, 8597, 17853, 36883, 75856, 155396, 317228, 645580, 1310132, 2652072, 5356277, 10795351, 21716195, 43608549, 87429944, 175025918, 349901074, 698604058, 1393149486, 2775103948, 5522129511, 10977608425
Offset: 0

Views

Author

Vladimir Kruchinin, Jan 17 2018

Keywords

Crossrefs

Cf. A000078.

Programs

  • Maxima
    a(n):=sum(sum(i*binomial(m-i,i)*binomial(m-i,n-m-i),i,0,m),m,0,n);
    
  • PARI
    concat(vector(2), Vec(x^2*(1 + x) / (1 - x - x^2 - x^3 - x^4)^2 + O(x^40))) \\ Colin Barker, Jan 18 2018

Formula

G.f.: x^3*(1 + x) / (1 - x - x^2 - x^3 - x^4)^2.
a(n) = 2*a(n-1) + a(n-2) - a(n-4) - 4*a(n-5) - 3*a(n-6) - 2*a(n-7) - a(n-8) for n>7. - Colin Barker, Jan 18 2018

A309703 G.f. A(x) satisfies: A(x) = A(x^2) / (1 - x - x^2 - x^3 - x^4).

Original entry on oeis.org

1, 1, 3, 5, 13, 22, 48, 88, 184, 342, 684, 1298, 2556, 4880, 9506, 18240, 35366, 67992, 131446, 253044, 488532, 941014, 1815334, 3497924, 6745360, 12999632, 25063130, 48306046, 93123674, 179492482, 346003572, 666925774, 1285580868, 2478002696, 4776580902, 9207090240
Offset: 0

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Author

Ilya Gutkovskiy, Aug 13 2019

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 35; A[] = 1; Do[A[x] = A[x^2]/(1 - x - x^2 - x^3 - x^4) + O[x]^(nmax + 1) // Normal, nmax + 1]; CoefficientList[A[x], x]
    nmax = 35; CoefficientList[Series[Product[1/(1 - x^(2^k) - x^(2^(k + 1)) - x^(3 2^k) - x^(2^(k + 2))), {k, 0, Floor[Log[2, nmax]] + 1}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=0} 1/(1 - x^(2^k) - x^(2^(k+1)) - x^(3*2^k) - x^(2^(k+2))).

A349903 Array read by ascending antidiagonals. Inverse Euler transform of the right-shifted k-bonacci numbers.

Original entry on oeis.org

0, 0, 1, 0, 1, 0, 0, 1, 1, -1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 2, -1, 0, 0, 0, 0, 1, 2, 2, 0, 0, 0, 0, 0, 0, 1, 3, 4, 0, 0, 0, 0, 0, 0, 1, 2, 6, 5, 0, 0, 0, 0, 0, 0, 0, 1, 4, 10, 8, 0, 0, 0, 0, 0, 0, 0, 1, 2, 7, 18, 11, 0, 0, 0, 0, 0, 0, 0, 0, 1, 4, 14, 31, 18, 0, 0
Offset: 0

Views

Author

Peter Luschny, Dec 05 2021

Keywords

Examples

			Array starts:
[0] 0, 1, 0, -1, 0,  0, 0,  0,  0,  0,  0,  0,   0, ...
[1] 0, 1, 1,  0, 0, -1, 0,  0,  0,  0,  0,  0,   0, ...
[2] 0, 1, 1,  1, 2,  2, 4,  5,  8, 11, 18, 25,  40, ...
[3] 0, 0, 1,  1, 2,  3, 6, 10, 18, 31, 56, 96, 172, ...
[4] 0, 0, 0,  1, 1,  2, 4,  7, 14, 26, 50, 93, 178, ...
[5] 0, 0, 0,  0, 1,  1, 2,  4,  8, 15, 30, 58, 114, ...
[6] 0, 0, 0,  0, 0,  1, 1,  2,  4,  8, 16, 31,  62, ...
[7] 0, 0, 0,  0, 0,  0, 1,  1,  2,  4,  8, 16,  32, ...
[8] 0, 0, 0,  0, 0,  0, 0,  1,  1,  2,  4,  8,  16, ...
[9] 0, 0, 0,  0, 0,  0, 0,  0,  1,  1,  2,  4,   8, ...
.
Compare the rows with the columns of A349802.
		

Crossrefs

Rows are the inverse Euler transforms of A063524, A057427, A000045, A000073, A000078, A001591, A001592.

Programs

  • Maple
    read transforms;
    F := proc(n, k) option remember;
         ifelse(k < 2, k, add(F(n, k-j), j = 1..min(n, k))) end:
    Frow := (n, len) -> [seq(0, j = 0..n-3), seq(F(n, k), k = 0..len)]:
    Arow := (n, len) -> EULERi(Frow(n, len)):
    for n from 0 to 9 do Arow(n, 14 - n) od;

A356807 Tetranacci sequence beginning with 3, 7, 12, 24.

Original entry on oeis.org

3, 7, 12, 24, 46, 89, 171, 330, 636, 1226, 2363, 4555, 8780, 16924, 32622, 62881, 121207, 233634, 450344, 868066, 1673251, 3225295, 6216956, 11983568, 23099070, 44524889, 85824483, 165432010, 318880452, 614661834, 1184798779, 2283773075, 4402114140, 8485347828
Offset: 1

Views

Author

Greg Dresden and Hangyu Liang, Aug 29 2022

Keywords

Comments

By "Tetranacci sequence" we mean a sequence in which each term is the sum of the four previous terms.
For n>1, a(n) is the number of ways to tile this figure of length n with squares, dominoes, trominoes, and tetraminoes:
_
|||_________ _
|||_|||_|| ... ||

Examples

			Here is one of the a(6) = 89 ways to tile this figure of length 6 with tiles of length <= 4, this one using three squares, one domino, and one tromino:
   ___
  | |_|_______
  |_|_____|_|_|
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{1, 1, 1, 1}, {3, 7, 12, 24}, 50] (* Paolo Xausa, Aug 30 2024 *)

Formula

a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4).
a(n) = 5*b(n+2) + 2*b(n+1) - 2*b(n-2) for b(n) = A000078(n) the tetranacci numbers.
a(n) = L(n+2) - F(n-2) + Sum_{k=0..n-3} a(k)*F(n-k-1), for L(n) and F(n) the Lucas and Fibonacci numbers.
G.f.: x*(-2*x^3 - 2*x^2 - 4*x - 3)/(x^4 + x^3 + x^2 + x - 1). - Chai Wah Wu, Aug 30 2022

A093175 Tetranacci numbers starting with first four squares.

Original entry on oeis.org

1, 4, 9, 16, 30, 59, 114, 219, 422, 814, 1569, 3024, 5829, 11236, 21658, 41747, 80470, 155111, 298986, 576314, 1110881, 2141292, 4127473, 7955960, 15335606, 29560331, 56979370, 109831267, 211706574, 408077542, 786594753, 1516210136, 2922589005
Offset: 1

Views

Author

Jun Mizuki (suzuki32(AT)sanken.osaka-u.ac.jp), May 11 2004

Keywords

Crossrefs

Cf. A086192.

Programs

  • Mathematica
    a[1] = 1; a[2] = 4; a[3] = 9; a[4] = 16; a[n_] := a[n] = a[n - 1] + a[n - 2] + a[n - 3] + a[n - 4]; Table[ a[n], {n, 33}] (* Robert G. Wilson v *)
    LinearRecurrence[{1,1,1,1},Range[4]^2,40] (* Harvey P. Dale, Oct 16 2012 *)

Formula

a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4).
G.f.: -x*(1+x)*(2*x^2+2*x+1)/(-1+x+x^2+x^3+x^4). a(n)=2*A000078(n+3)+2*A000078(n)-A001631(n+1). [R. J. Mathar, Apr 20 2009]

Extensions

More terms from Robert G. Wilson v and Labos Elemer, May 12 2004, May 11 2004

A111432 Fibonacci(tetranacci(n)).

Original entry on oeis.org

0, 0, 0, 1, 1, 1, 3, 21, 610, 514229, 225851433717, 16641027750620563662096, 13180872826374098837632191485015125807374171, 284812298108489611757988937681460995615380088782304890986477195645969271404032323901
Offset: 0

Views

Author

Jonathan Vos Post, Nov 13 2005

Keywords

Examples

			a(0) = Fibonacci(tetranacci(0)) = A000045(A000078(0)) = A000045(0) = 0.
a(1) = Fibonacci(tetranacci(1)) = A000045(A000078(1)) = A000045(0) = 0.
a(2) = Fibonacci(tetranacci(2)) = A000045(A000078(2)) = A000045(0) = 0.
a(3) = Fibonacci(tetranacci(3)) = A000045(A000078(3)) = A000045(1) = 1.
a(4) = Fibonacci(tetranacci(4)) = A000045(A000078(4)) = A000045(1) = 1.
a(5) = A000045(A000078(5)) = A000045(2) = 1.
a(6) = A000045(A000078(6)) = A000045(4) = 3.
a(7) = A000045(A000078(7)) = A000045(8) = 21.
a(8) = A000045(A000078(8)) = A000045(15) = 610.
a(9) = A000045(A000078(9)) = A000045(29) = 514229.
a(10) = A000045(A000078(10)) = A000045(56) = 225851433717.
		

Crossrefs

Programs

  • Mathematica
    Fibonacci[LinearRecurrence[{1,1,1,1},{0,0,0,1},14]] (* Harvey P. Dale, Aug 03 2017 *)

Formula

a(n) = A000045(A000078(n)).

A255014 Abelian complexity function of the 4-bonacci word (A254990).

Original entry on oeis.org

4, 4, 6, 4, 7, 6, 7, 4, 7, 7, 8, 6, 8, 7, 7, 4, 7, 7, 8, 7, 8, 8, 7, 7, 8, 8, 7, 8, 7, 7, 4, 7, 7, 8, 7, 8, 8, 8, 7, 8, 8, 8, 8, 7, 7, 7, 7, 8, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 4, 7, 8, 9, 7, 8, 9, 9, 7, 8, 10, 10, 8, 8, 8, 8, 7, 9, 10, 9, 8, 9, 9, 8, 8, 9, 10, 7, 8, 7, 8, 7, 8, 9, 9, 8, 8, 8, 8, 8, 7
Offset: 1

Views

Author

Ondrej Turek, Feb 12 2015

Keywords

Comments

For all n, a(n) either equals 4 or belongs to {6,7,...,16}; value 5 is never attained.
a(n)=4 if and only if n = T(k)+T(k-4)+T(k-8)+T(k-12)+...+T(4+(k mod 4)) for a certain k>=4, where T(i) are tetranacci numbers A000078.
a(n)=6 only for n = 3,6,12.
Each value from the set {7,8,...,16} is attained infinitely often.

Examples

			From _Wolfdieter Lang_, Mar 26 2015: (Start)
a(1) = 4 because the one letter factor words of A254990 are 0, 1, 2, 3 with the set of occurrence tuples (Parikh vectors) {(1, 0, 0, 0), (0, 1, 0, 0), (0, 0, 1, 0), (0, 0, 0, 1)} of cardinality 4. See the Turek links.
a(2) = 4 because the set of occurrence tuples for the two letter factors 00, 01, 10, 02, 20, 03, 30 of A254990 is {(2, 0, 0, 0), (1, 1, 0, 0), (1, 0, 1, 0), (1, 0, 0, 1)} of cardinality 4. (End)
		

Crossrefs

Cf. A000078 (tetranacci numbers).
Cf. A216190 (abelian complexity of tribonacci word), A254990 (4-bonacci word).

A364145 a(n) is the sum of the first 2*n nonzero n-bonacci numbers.

Original entry on oeis.org

0, 2, 7, 28, 116, 480, 1968, 8000, 32320, 130048, 521984, 2092032, 8377344, 33529856, 134164480, 536756224, 2147237888, 8589410304, 34358624256, 137436594176, 549750833152, 2199012769792, 8796071002112, 35184325951488, 140737391886336, 562949752094720
Offset: 0

Views

Author

Muhammad Adam Dombrowski and Greg Dresden, Jul 10 2023

Keywords

Comments

For our purposes, for n > 0 fixed we define the k-th n-bonacci number T(n,k) as equal to 0 for k <= 0, equal to 1 for k=1, and then equal to the sum of the previous n numbers for k > 1. For n=2, then, we get T(2,k) equal to F(n) = A000045(n), the Fibonacci numbers. For n=3, then, T(3,k) is the tribonacci numbers, and so on.
a(n) is thus defined as Sum_{k=1..2*n} T(n,k).

Examples

			For n=3, a(3) is the sum of the first 6 nonzero tribonacci numbers, found at A000073. This gives a(3) = 1 + 1 + 2 + 4 + 7 + 13 = 28.
		

Crossrefs

Programs

  • Mathematica
    T[n_, k_] := SeriesCoefficient[Series[x/(1 - Sum[x^i, {i, 1, n}]), {x, 0, k + 1}], k]; Table[Sum[T[n, k], {k, 1, 2n}], {n, 1, 30}]

Formula

a(n) = (2*4^n - (n-1)*2^n)/4 for n>=1.
a(n) = Sum_{i=1..2*n} A092921(n,i).
G.f.: -x*(12*x^2-9*x+2)/((4*x-1)*(2*x-1)^2). - Alois P. Heinz, Jul 11 2023
E.g.f.: exp(2*x)*(1 - 2*x - cosh(2*x) + 5*sinh(2*x))/4. - Stefano Spezia, Jul 12 2023

A365293 a(n) = n!*tetranacci(n+3).

Original entry on oeis.org

1, 1, 4, 24, 192, 1800, 20880, 282240, 4354560, 75479040, 1455148800, 30855686400, 713712384000, 17884003737600, 482619020083200, 13954193180928000, 430360865206272000, 14102295149150208000, 489295008086556672000, 17919783031425859584000
Offset: 0

Views

Author

Enrique Navarrete, Aug 31 2023

Keywords

Comments

a(n) is the number of ways to partition [n] into blocks of size at most 4, order the blocks, and order the elements within each block.

Examples

			a(5) = 1800 since the number of ways to partition [5] into blocks of size at most 4, order the blocks, and order the elements within each block are the following:
1) 1234,5: 10 such ordered blocks; 240 ways;
2) 123,4,5: 60 such ordered blocks; 360 ways;
3) 123,45: 20 such ordered blocks; 240 ways;
4) 12,34,5: 90 such ordered blocks; 360 ways;
5) 12,3,4,5: 240 such ordered blocks; 480 ways;
6) 1,2,3,4,5: 120 such ordered blocks; 120 ways.
		

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[1/(1-x-x^2-x^3-x^4),{x,0,n}],{n,0,19}] (* Stefano Spezia, Aug 31 2023 *)

Formula

E.g.f.: 1/(1-x-x^2-x^3-x^4).
a(n) = A000142(n) * A000078(n+3).
Previous Showing 91-100 of 100 results.