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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A214830 a(n) = a(n-1) + a(n-2) + a(n-3), with a(0) = 1, a(1) = a(2) = 8.

Original entry on oeis.org

1, 8, 8, 17, 33, 58, 108, 199, 365, 672, 1236, 2273, 4181, 7690, 14144, 26015, 47849, 88008, 161872, 297729, 547609, 1007210, 1852548, 3407367, 6267125, 11527040, 21201532, 38995697, 71724269, 131921498, 242641464, 446287231, 820850193, 1509778888
Offset: 0

Views

Author

Abel Amene, Aug 07 2012

Keywords

Comments

See comments in A214727.

Crossrefs

Programs

  • GAP
    a:=[1,8,8];; for n in [4..40] do a[n]:=a[n-1]+a[n-2]+a[n-3]; od; a; # G. C. Greubel, Apr 24 2019
  • Magma
    R:=PowerSeriesRing(Integers(), 40); Coefficients(R!( (1+7*x-x^2)/(1-x-x^2-x^3) )); // G. C. Greubel, Apr 24 2019
    
  • Mathematica
    CoefficientList[Series[(x^2-7*x-1)/(x^3+x^2+x-1), {x, 0, 40}], x] (* Wesley Ivan Hurt, Jun 18 2014 *)
    LinearRecurrence[{1,1,1}, {1,8,8}, 40] (* G. C. Greubel, Apr 24 2019 *)
  • PARI
    my(x='x+O('x^40)); Vec((1+7*x-x^2)/(1-x-x^2-x^3)) \\ G. C. Greubel, Apr 24 2019
    
  • Sage
    ((1+7*x-x^2)/(1-x-x^2-x^3)).series(x, 40).coefficients(x, sparse=False) # G. C. Greubel, Apr 24 2019
    

Formula

G.f.: (1+7*x-x^2)/(1-x-x^2-x^3).
a(n) = -A000073(n) + 7*A000073(n+1) + A000073(n+2). - G. C. Greubel, Apr 24 2019

A247192 Indices of primes in the hexanacci numbers sequence A000383.

Original entry on oeis.org

7, 9, 30, 31, 33, 46, 52, 54, 82, 102, 109, 124, 210, 301, 351, 365, 369, 1045, 2044, 2125, 2143, 2815, 4377, 4754, 4893, 7310, 11558, 17602, 17929, 28389, 32100, 44298, 106725, 151678, 197953
Offset: 1

Views

Author

Robert Price, Dec 03 2014

Keywords

Comments

a(36) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={1,1,1,1,1}; For[n=5, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[5]]=sum]

A248920 Indices of primes in the pentanacci numbers sequence A000322.

Original entry on oeis.org

5, 7, 13, 18, 19, 34, 35, 38, 43, 48, 188, 286, 450, 501, 759, 1446, 2021, 2419, 2997, 3715, 5677, 13566, 46303, 57174, 108844, 117145, 166683, 178863
Offset: 1

Views

Author

Robert Price, Oct 16 2014

Keywords

Comments

a(29) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={1,1,1,1,1}; For[n=5, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[5]]=sum]

A251654 4-step Fibonacci sequence starting with 0, 1, 1, 0.

Original entry on oeis.org

0, 1, 1, 0, 2, 4, 7, 13, 26, 50, 96, 185, 357, 688, 1326, 2556, 4927, 9497, 18306, 35286, 68016, 131105, 252713, 487120, 938954, 1809892, 3488679, 6724645, 12962170, 24985386, 48160880, 92833081, 178941517, 344920864, 664856342, 1281551804
Offset: 0

Views

Author

Arie Bos, Dec 06 2014

Keywords

Crossrefs

Other 4-step Fibonacci sequences are A000078, A000288, A001630, A001631, A001648, A073817, A100532, A251655, A251656, A251672, A251703, A251704, A251705.

Programs

  • J
    NB. see A251655 for the program and apply it to 0,1,1,0.
  • Mathematica
    LinearRecurrence[Table[1, {4}], {0, 1, 1, 0}, 36] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+4) = a(n) + a(n+1) + a(n+2) + a(n+3).
G.f.: x*(-1+2*x^2)/(-1+x+x^2+x^3+x^4). - R. J. Mathar, Mar 28 2025
a(n) = A000078(n+2)-2*A000078(n). - R. J. Mathar, Mar 28 2025

A251655 4-step Fibonacci sequence starting with 0, 1, 1, 1.

Original entry on oeis.org

0, 1, 1, 1, 3, 6, 11, 21, 41, 79, 152, 293, 565, 1089, 2099, 4046, 7799, 15033, 28977, 55855, 107664, 207529, 400025, 771073, 1486291, 2864918, 5522307, 10644589, 20518105, 39549919, 76234920, 146947533, 283250477, 545982849, 1052415779, 2028596638
Offset: 0

Views

Author

Arie Bos, Dec 06 2014

Keywords

Crossrefs

Other 4-step Fibonacci sequences are A000078, A000288, A001630, A001631, A001648, A073817, A100532, A251654, A251656, A251672, A251703, A251704, A251705.

Programs

  • J
    (see www.jsoftware.com) First construct the generating matrix
       [M=: (#.@}: + {:)\"1&.|: <:/~i.4
    1 1 1 1
    1 2 2 2
    2 3 4 4
    4 6 7 8
    Given that matrix, one can produce the first 4*250 numbers with
    , M(+/ . *)^:(i.250) 0 1 1 1x
  • Mathematica
    LinearRecurrence[Table[1, {4}], {0, 1, 1, 1}, 36] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+4) = a(n) + a(n+1) + a(n+2) + a(n+3).
G.f.: x*(x-1)*(1+x)/(-1+x+x^2+x^3+x^4) . - R. J. Mathar, Mar 28 2025
a(n) = A000078(n+2)-A000078(n). - R. J. Mathar, Mar 28 2025

A251704 4-step Fibonacci sequence starting with 1, 1, 0, 1.

Original entry on oeis.org

1, 1, 0, 1, 3, 5, 9, 18, 35, 67, 129, 249, 480, 925, 1783, 3437, 6625, 12770, 24615, 47447, 91457, 176289, 339808, 655001, 1262555, 2433653, 4691017, 9042226, 17429451, 33596347, 64759041, 124827065, 240611904, 463794357, 893992367, 1723225693
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Crossrefs

Other 4-step Fibonacci sequences are A000078, A000288, A001630, A001631, A001648, A073817, A100532, A251654, A251655, A251656, A251703, A251705.

Programs

  • J
    NB. see A251655 for the program and apply it to 1,1,0,1.
  • Mathematica
    LinearRecurrence[Table[1, {4}], {1, 1, 0, 1}, 36] (* Michael De Vlieger, Dec 09 2014 *)

Formula

a(n+4) = a(n) + a(n+1) + a(n+2) + a(n+3).
G.f.: (1+x)*(x^2+x-1)/(-1+x+x^2+x^3+x^4) . - R. J. Mathar, Mar 28 2025
a(n) = A001630(n-2)+A001630(n-1), n>2. - R. J. Mathar, Mar 28 2025

A251705 4-step Fibonacci sequence starting with 1, 1, 1, 0.

Original entry on oeis.org

1, 1, 1, 0, 3, 5, 9, 17, 34, 65, 125, 241, 465, 896, 1727, 3329, 6417, 12369, 23842, 45957, 88585, 170753, 329137, 634432, 1222907, 2357229, 4543705, 8758273, 16882114, 32541321, 62725413, 120907121, 233055969, 449229824, 865918327, 1669111241
Offset: 0

Views

Author

Arie Bos, Dec 07 2014

Keywords

Crossrefs

Other 4-step Fibonacci sequences are A000078, A000288, A001630, A001631, A001648, A073817, A100532, A251654, A251655, A251656, A251703, A251704.

Programs

  • J
    NB. see A251655 for the program and apply it to 1,1,1,0.
  • Mathematica
    LinearRecurrence[Table[1, {4}], {1, 1, 1, 0}, 36] (* Michael De Vlieger, Dec 09 2014 *)

Formula

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

A253318 Indices of primes in the 7th-order Fibonacci number sequence, A060455.

Original entry on oeis.org

7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 21, 23, 26, 32, 33, 36, 42, 44, 71, 72, 137, 180, 193, 285, 679, 955, 1018, 1155, 1176, 1191, 2149, 2590, 2757, 3364, 4233, 6243, 6364, 7443, 10194, 11254, 13318, 18995, 20478, 22647, 29711, 34769, 61815, 71993, 107494, 135942, 148831
Offset: 1

Views

Author

Robert Price, Dec 30 2014

Keywords

Comments

a(52) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={1,1,1,1,1,1,1}; step=7; lst={}; For[n=step,n<=1000,n++, sum=Plus@@a; If[PrimeQ[sum], AppendTo[lst,n]]; a=RotateLeft[a]; a[[7]]=sum]; lst

A061451 Array T(n,k) of k-th order Fibonacci numbers read by antidiagonals in up-direction.

Original entry on oeis.org

2, 3, 3, 4, 5, 5, 5, 7, 9, 8, 6, 9, 13, 17, 13, 7, 11, 17, 25, 31, 21, 8, 13, 21, 33, 49, 57, 34, 9, 15, 25, 41, 65, 94, 105, 55, 10, 17, 29, 49, 81, 129, 181, 193, 89, 11, 19, 33, 57, 97, 161, 253, 349, 355, 144, 12, 21, 37, 65, 113, 193, 321, 497, 673, 653, 233
Offset: 1

Views

Author

Frank Ellermann, Jun 11 2001

Keywords

Examples

			2, 3, 5, 8 ... first order, a(1)=2, a(3)=3, a(6)=5, a(10)=8, ...
3, 5, 9,17 ... 2nd order, a(2)=3, a(5)=5, a(9)=9, ...
4, 7,13,25 ... 3rd order, a(4)=4, a(8)=7, ...
5, 9,17,33 ... 4th order, a(7)=5, ...
		

References

  • N. Wirth, Algorithmen und Datenstrukturen, 1975, table 2.15 (ch. 2.3.4)

Crossrefs

Programs

  • Mathematica
    max = 12; Clear[f]; f[k_, n_] /; n > k := f[k, n] = Sum[f[k, n - j], {j, 1, k + 1}]; f[k_, n_] = 1; t = Table[ Table[ f[k, n], {n, k + 1, max}], {k, 1, max}]; Table[ t[[k - n + 1, n]], {k, 1, max - 1}, {n, 1, k}] // Flatten (* Jean-François Alcover, Apr 10 2013 *)

A207539 Dodecanacci numbers (12th-order Fibonacci sequence): a(n) = a(n-1) +...+ a(n-12) with a(0)=...=a(11)=1.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 12, 23, 45, 89, 177, 353, 705, 1409, 2817, 5633, 11265, 22529, 45057, 90102, 180181, 360317, 720545, 1440913, 2881473, 5762241, 11523073, 23043329, 46081025, 92150785, 184279041, 368513025, 736935948, 1473691715
Offset: 0

Views

Author

Michael Burkhart, Feb 18 2012

Keywords

Crossrefs

Programs

  • Maple
    f12:=proc(n) option remember: if n<=12 then 1: else add(f12(n-i),i=1..12): fi: end:
  • Mathematica
    LinearRecurrence[Table[1, {12}], Table[1, {12}], 100]
  • PARI
    x='x+O('x^50); Vec((1-x-x^2-x^3-x^4-x^5-x^6-x^7-x^8-x^9-x^10-x^11 +10*x^12)/(1-2*x+x^13)) \\ G. C. Greubel, Jul 28 2017

Formula

G.f.: (1-x-x^2-x^3-x^4-x^5-x^6-x^7-x^8-x^9-x^10-x^11 +10*x^12)/(1 -2*x +x^13).
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