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.

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A251710 7-step Fibonacci sequence starting with (0,0,0,0,0,1,0).

Original entry on oeis.org

0, 0, 0, 0, 0, 1, 0, 1, 2, 4, 8, 16, 32, 63, 126, 251, 500, 996, 1984, 3952, 7872, 15681, 31236, 62221, 123942, 246888, 491792, 979632, 1951392, 3887103, 7742970, 15423719, 30723496, 61200104, 121908416, 242837200, 483723008, 963558913, 1919374856, 3823325993
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Comments

a(n+7) equals the number of n-length binary words avoiding runs of zeros of lengths 7i+6, (i=0,1,2,...). - Milan Janjic, Feb 26 2015

Crossrefs

Other 7-step Fibonacci sequences are A066178, A104621, A122189, A251711, A251712, A251713, A251714.

Programs

  • J
    NB. see A251713 for the program and apply it to 0 0 0 0 0 1 0.
  • Mathematica
    LinearRecurrence[Table[1, {7}], {0, 0, 0, 0, 0, 1, 0}, 40] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+7) = a(n) + a(n+1) + a(n+2) + a(n+3) + a(n+4) + a(n+5) + a(n+6).
G.f.: x^5*(x-1)/(-1+x+x^2+x^3+x^4+x^5+x^6+x^7) . - R. J. Mathar, Mar 28 2025
a(n) = A066178(n-5)-A066178(n-6). - R. J. Mathar, Mar 28 2025

A251711 7-step Fibonacci sequence starting with (0,0,0,0,1,0,0).

Original entry on oeis.org

0, 0, 0, 0, 1, 0, 0, 1, 2, 4, 8, 16, 31, 62, 124, 247, 492, 980, 1952, 3888, 7745, 15428, 30732, 61217, 121942, 242904, 483856, 963824, 1919903, 3824378, 7618024, 15174831, 30227720, 60212536, 119941216, 238918608, 475917313, 948010248, 1888402472, 3761630113
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Crossrefs

Other 7-step Fibonacci sequences are A066178, A104621, A122189, A251710, A251712, A251713, A251714.

Programs

  • J
    NB. see A251713 for the program and apply it to 0 0 0 0 1 0 0.
  • Mathematica
    LinearRecurrence[Table[1, {7}], {0, 0, 0, 0, 1, 0, 0}, 40] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+7) = a(n) + a(n+1) + a(n+2) + a(n+3) + a(n+4) + a(n+5) + a(n+6).
G.f.: x^4*(-1+x+x^2)/(-1+x+x^2+x^3+x^4+x^5+x^6+x^7) . - R. J. Mathar, Mar 28 2025
a(n) = A066178(n-4)-A066178(n-5)-A066178(n-6). - R. J. Mathar, Mar 28 2025

A251712 7-step Fibonacci sequence starting with (0,0,0,1,0,0,0).

Original entry on oeis.org

0, 0, 0, 1, 0, 0, 0, 1, 2, 4, 8, 15, 30, 60, 120, 239, 476, 948, 1888, 3761, 7492, 14924, 29728, 59217, 117958, 234968, 468048, 932335, 1857178, 3699432, 7369136, 14679055, 29240152, 58245336, 116022624, 231112913, 460368648, 917037864, 1826706592, 3638734129
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Crossrefs

Other 7-step Fibonacci sequences are A066178, A104621, A122189, A251710, A251711, A251713, A251714.

Programs

  • J
    NB. see A251713 for the program and apply it to 0 0 0 1 0 0 0.
  • Mathematica
    LinearRecurrence[Table[1, {7}], {0, 0, 0, 1, 0, 0, 0}, 40] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+7) = a(n) + a(n+1) + a(n+2) + a(n+3) + a(n+4) + a(n+5) + a(n+6).
G.f.: x^3*(-1+x+x^2+x^3)/(-1+x+x^2+x^3+x^4+x^5+x^6+x^7) . - R. J. Mathar, Mar 28 2025

A251713 7-step Fibonacci sequence starting with (0,0,1,0,0,0,0).

Original entry on oeis.org

0, 0, 1, 0, 0, 0, 0, 1, 2, 4, 7, 14, 28, 56, 112, 223, 444, 884, 1761, 3508, 6988, 13920, 27728, 55233, 110022, 219160, 436559, 869610, 1732232, 3450544, 6873360, 13691487, 27272952, 54326744, 108216929, 215564248, 429396264, 855341984, 1703810608, 3393929729
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Crossrefs

Other 7-step Fibonacci sequences are A066178, A104621, A122189, A251710, A251711, A251712, A251714.

Programs

  • J
    (see www.jsoftware.com) First construct the generating matrix
       [M=: (#.@}: + {:)\"1&.|: <:/~i.7
     1  1  1  1  1  1  1
     1  2  2  2  2  2  2
     2  3  4  4  4  4  4
     4  6  7  8  8  8  8
     8 12 14 15 16 16 16
    16 24 28 30 31 32 32
    32 48 56 60 62 63 64
    Given that matrix, one can produce the first 7*150 numbers by
    , M(+/ . *)^:(i.150) 0 0 1 0 0 0 0x
  • Mathematica
    LinearRecurrence[Table[1, {7}], {0, 0, 1, 0, 0, 0, 0}, 40] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+7) = a(n) + a(n+1) + a(n+2) + a(n+3) + a(n+4) + a(n+5) + a(n+6).
G.f.: x^2*(-1+x+x^2+x^3+x^4)/(-1+x+x^2+x^3+x^4+x^5+x^6+x^7) . - R. J. Mathar, Mar 28 2025

A251714 7-step Fibonacci sequence starting with (0,1,0,0,0,0,0).

Original entry on oeis.org

0, 1, 0, 0, 0, 0, 0, 1, 2, 3, 6, 12, 24, 48, 96, 191, 380, 757, 1508, 3004, 5984, 11920, 23744, 47297, 94214, 187671, 373834, 744664, 1483344, 2954768, 5885792, 11724287, 23354360, 46521049, 92668264, 184591864, 367700384, 732446000, 1459006208, 2906288129
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Crossrefs

Other 7-step Fibonacci sequences are A066178, A104621, A122189, A251710, A251711, A251712, A251713.

Programs

  • J
    NB. see A251713 for the program and apply it to 0 1 0 0 0 0 0.
  • Mathematica
    LinearRecurrence[Table[1, {7}], {0, 1, 0, 0, 0, 0, 0}, 40] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+7) = a(n) + a(n+1) + a(n+2) + a(n+3) + a(n+4) + a(n+5) + a(n+6).
G.f.: x*(-1+x+x^2+x^3+x^4+x^5)/(-1+x+x^2+x^3+x^4+x^5+x^6+x^7) . - R. J. Mathar, Mar 28 2025

A105758 Indices of prime hexanacci (or Fibonacci 6-step) numbers A001592 (using offset -4).

Original entry on oeis.org

3, 36, 37, 92, 660, 6091, 8415, 11467, 13686, 38831, 49828, 97148
Offset: 1

Views

Author

T. D. Noe, Apr 22 2005

Keywords

Comments

No other n < 30000.
This sequence uses the convention of the Noe and Post reference. Their indexing scheme differs by 4 from the indices in A001592. Sequence A249635 lists the indices of the same primes (A105759) using the indexing scheme as defined in A001592. - Robert Price, Nov 02 2014 [Edited by M. F. Hasler, Apr 22 2018]
a(13) > 3*10^5. - Robert Price, Nov 02 2014

Crossrefs

Cf. A105759 (prime Fibonacci 6-step numbers), A249635 (= a(n) + 4), A001592.
Cf. A000045, A000073, A000078 (and A001631), A001591, A122189 (or A066178), A079262, A104144, A122265, A168082, A168083 (Fibonacci, tribonacci, tetranacci numbers and other generalizations).
Cf. A005478, A092836, A104535, A105757, A105761, ... (primes in these sequence).
Cf. A001605, A303263, A303264 (and A104534 and A247027), A248757 (and A105756), ... (indices of primes in A000045, A000073, A000078, ...).

Programs

  • Mathematica
    a={1, 0, 0, 0, 0, 0}; lst={}; Do[s=Plus@@a; a=RotateLeft[a]; a[[ -1]]=s; If[PrimeQ[s], AppendTo[lst, n]], {n, 30000}]; lst

Formula

a(n) = A249635(n) - 4. A105759(n) = A001592(A249635(n)) = A001592(a(n) + 4). - M. F. Hasler, Apr 22 2018

Extensions

a(10)-a(12) from Robert Price, Nov 02 2014
Edited by M. F. Hasler, Apr 22 2018

A247506 Generalized Fibonacci numbers: square array A(n,k) read by ascending antidiagonals, A(n,k) = [x^k]((1-Sum_{j=1..n} x^j)^(-1)), (n>=0, k>=0).

Original entry on oeis.org

1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 1, 0, 1, 1, 2, 3, 1, 0, 1, 1, 2, 4, 5, 1, 0, 1, 1, 2, 4, 7, 8, 1, 0, 1, 1, 2, 4, 8, 13, 13, 1, 0, 1, 1, 2, 4, 8, 15, 24, 21, 1, 0, 1, 1, 2, 4, 8, 16, 29, 44, 34, 1, 0, 1, 1, 2, 4, 8, 16, 31, 56, 81, 55, 1, 0
Offset: 0

Views

Author

Peter Luschny, Nov 02 2014

Keywords

Examples

			[n\k] [0][1][2][3][4] [5] [6] [7]  [8]  [9] [10]  [11]  [12]
   [0] 1, 0, 0, 0, 0,  0,  0,  0,   0,   0,   0,    0,    0
   [1] 1, 1, 1, 1, 1,  1,  1,  1,   1,   1,   1,    1,    1
   [2] 1, 1, 2, 3, 5,  8, 13, 21,  34,  55,  89,  144,  233  [A000045]
   [3] 1, 1, 2, 4, 7, 13, 24, 44,  81, 149, 274,  504,  927  [A000073]
   [4] 1, 1, 2, 4, 8, 15, 29, 56, 108, 208, 401,  773, 1490  [A000078]
   [5] 1, 1, 2, 4, 8, 16, 31, 61, 120, 236, 464,  912, 1793  [A001591]
   [6] 1, 1, 2, 4, 8, 16, 32, 63, 125, 248, 492,  976, 1936  [A001592]
   [7] 1, 1, 2, 4, 8, 16, 32, 64, 127, 253, 504, 1004, 2000  [A066178]
   [8] 1, 1, 2, 4, 8, 16, 32, 64, 128, 255, 509, 1016, 2028  [A079262]
   [.] .  .  .  .  .   .   .   .    .    .    .     .     .
  [oo] 1, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048  [A011782]
.
As a triangular array, starts:
  1,
  1, 0,
  1, 1, 0,
  1, 1, 1, 0,
  1, 1, 2, 1, 0,
  1, 1, 2, 3, 1, 0,
  1, 1, 2, 4, 5, 1, 0,
  1, 1, 2, 4, 7, 8, 1, 0,
  1, 1, 2, 4, 8, 13, 13, 1, 0,
  1, 1, 2, 4, 8, 15, 24, 21, 1, 0,
  ...
		

Crossrefs

Programs

  • Maple
    A := (n,k) -> coeff(series((1-add(x^j, j=1..n))^(-1),x,k+2),x,k):
    seq(print(seq(A(n,k), k=0..12)), n=0..9);
  • Mathematica
    A[n_, k_] := A[n, k] = If[k<0, 0, If[k==0, 1, Sum[A[n, j], {j, k-n, k-1}]]]; Table[A[n-k, k], {n, 0, 11}, {k, 0, n}] // Flatten (* Jean-François Alcover, Jul 08 2019 *)

Formula

A(n, k) = Sum_{j=0..floor(k/(n+1))} (-1)^j*((k - j*n) + j + delta(k,0))/(2*(k - j*n) + delta(k,0))*binomial(k - j*n, j)*2^(k-j*(n+1)), where delta denotes the Kronecker delta (see Corollary 3.2 in Parks and Wills). - Stefano Spezia, Aug 06 2022

A111431 a(n) = Fibonacci(tribonacci(n)).

Original entry on oeis.org

0, 0, 1, 1, 1, 3, 13, 233, 46368, 701408733, 37889062373143906, 6161314747715278029583501626149, 818706854228831001753880637535093596811413714795418360007
Offset: 0

Views

Author

Jonathan Vos Post, Nov 13 2005

Keywords

Examples

			a(0) = Fibonacci(tribonacci(0)) = A000045(A000073(0)) = A000045(0) = 0.
a(1) = Fibonacci(tribonacci(1)) = A000045(A000073(1)) = A000045(0) = 0.
a(2) = Fibonacci(tribonacci(2)) = A000045(A000073(2)) = A000045(1) = 1.
a(3) = Fibonacci(tribonacci(3)) = A000045(A000073(3)) = A000045(1) = 1.
a(4) = Fibonacci(tribonacci(4)) = A000045(A000073(4)) = A000045(2) = 1.
a(5) = Fibonacci(tribonacci(5)) = A000045(A000073(5)) = A000045(4) = 3.
a(6) = Fibonacci(tribonacci(6)) = A000045(A000073(6)) = A000045(7) = 13.
a(7) = Fibonacci(tribonacci(7)) = A000045(A000073(7)) = A000045(13) = 233.
a(8) = A000045(A000073(8)) = A000045(24) = 46368.
a(9) = A000045(A000073(9)) = A000045(44) = 701408733.
a(10) = A000045(A000073(10)) = A000045(81) = 37889062373143906.
		

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1>, <1|1>>^((<<0|1|0>, <0|0|1>, <1|1|1>>^n)[1, 3]))[1, 2]:
    seq(a(n), n=0..13);  # Alois P. Heinz, Aug 09 2018
  • Mathematica
    Fibonacci/@LinearRecurrence[{1,1,1},{0,0,1},15] (* Harvey P. Dale, Jan 04 2013 *)

Formula

a(n) = A000045(A000073(n)).

A151975 The number of ways one can flip seven consecutive tails (or heads) when flipping a coin n times.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 1, 3, 8, 20, 48, 112, 256, 576, 1279, 2811, 6126, 13256, 28512, 61008, 129952, 275712, 582913, 1228551, 2582048, 5412984, 11321744, 23631056, 49229312, 102377216, 212560127, 440668919, 912310222, 1886316324, 3895528632, 8035861664
Offset: 0

Views

Author

Benjamin Merkel, Aug 05 2012

Keywords

Comments

a(n-1) is the number of compositions of n with at least one part >=8. - Joerg Arndt, Aug 06 2012

Examples

			a(0)=0 means that there are no cases of seven consecutive tails (or heads) in zero coin flips.  Likewise, a(1)=a(2)=...=a(6)=0.  a(7)=1 since there is exactly one case of seven consecutive tails in seven coin flips.
		

Crossrefs

Programs

  • PARI
    N=66;  x='x+O('x^N);
    gf = (1-x)/(1-2*x); /* A011782(n): compositions of n */
    gf -= 1/(1 - (x+x^2+x^3+x^4+x^5+x^6+x^7)); /* A066178(n): compositions of n into parts <=7 */
    v151975=Vec(gf + 'a0);  v151975[1]=0; /* kludge to get all terms */
    v151975 /* show terms */
    /* Joerg Arndt, Aug 06 2012 */
    
  • PARI
    concat(vector(7), Vec(x^7/((2*x-1)*(x^7+x^6+x^5+x^4+x^3+x^2+x-1)) + O(x^100))) \\ Colin Barker, Oct 16 2015

Formula

a(n) = A000079(n) - A066178(n+1).
G.f.: x^7 / ((2*x-1)*(x^7+x^6+x^5+x^4+x^3+x^2+x-1)). - Colin Barker, Oct 16 2015

A303264 Indices of primes in tetranacci sequence A000078.

Original entry on oeis.org

5, 9, 13, 14, 38, 58, 403, 2709, 8419, 14098, 31563, 50698, 53194, 155184
Offset: 1

Views

Author

M. F. Hasler, Apr 18 2018

Keywords

Comments

T = A000078 is defined by T(n) = Sum_{k=1..4} T(n-k), T(3) = 1, T(n) = 0 for n < 3.
The largest terms correspond to unproven probable primes T(a(n)).

Crossrefs

Cf. A000045, A000073, A000078, A001591, A001592, A122189 (or A066178), ... (Fibonacci, tribonacci, tetranacci numbers).
Cf. A005478, A092836, A104535, A105757, A105759, A105761, ... (primes in Fibonacci numbers and above generalizations).
Cf. A001605, A303263, A303264, A248757, A249635, ... (indices of primes in A000045, A000073, A000078, ...).
Cf. A247027: Indices of primes in the tetranacci sequence A001631 (starting 0, 0, 1, 0...), A104534 (a variant: a(n) - 2), A105756 (= A248757 - 3), A105758 (= A249635 - 4).

Programs

  • PARI
    a(n,N=5,S=vector(N,i,i>N-2))={for(i=N,oo,ispseudoprime(S[i%N+1]=2*S[(i-1)%N+1]-S[i%N+1])&&!n--&&return(i))}

Formula

a(n) = A104534(n) + 2.
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