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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A255532 Indices of primes in the 9th-order Fibonacci number sequence, A251749.

Original entry on oeis.org

10, 14, 19, 29, 404, 1744, 8854, 27754
Offset: 1

Views

Author

Robert Price, Feb 24 2015

Keywords

Comments

a(9) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={0,0,0,0,1,0,0,0,0}; step=9; lst={}; For[n=step,n<=1000,n++, sum=Plus@@a; If[PrimeQ[sum], AppendTo[lst,n]]; a=RotateLeft[a]; a[[step]]=sum]; lst

A255533 Indices of primes in the 9th-order Fibonacci number sequence, A251750.

Original entry on oeis.org

10, 33, 43, 253, 1253, 2389
Offset: 1

Views

Author

Robert Price, Feb 24 2015

Keywords

Comments

a(7) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={0,0,0,1,0,0,0,0,0}; step=9; lst={}; For[n=step,n<=1000,n++, sum=Plus@@a; If[PrimeQ[sum], AppendTo[lst,n]]; a=RotateLeft[a]; a[[step]]=sum]; lst

A255534 Indices of primes in the 9th-order Fibonacci number sequence, A251751.

Original entry on oeis.org

10, 12, 232, 502
Offset: 1

Views

Author

Robert Price, Feb 24 2015

Keywords

Comments

a(5) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={0,0,1,0,0,0,0,0,0}; step=9; lst={}; For[n=step,n<=1000,n++, sum=Plus@@a; If[PrimeQ[sum], AppendTo[lst,n]]; a=RotateLeft[a]; a[[step]]=sum]; lst
    Flatten[Position[LinearRecurrence[Table[1,{9}],{0,0,1,0,0,0,0,0,0},510], ?(PrimeQ[#]&)]]-1 (* _Harvey P. Dale, Feb 27 2016 *)

A255536 Indices of primes in the 9th-order Fibonacci number sequence, A251752.

Original entry on oeis.org

10, 11, 21, 29, 301, 57089
Offset: 1

Views

Author

Robert Price, Feb 24 2015

Keywords

Comments

a(7) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={0,1,0,0,0,0,0,0,0}; step=9; lst={}; For[n=step,n<=1000,n++, sum=Plus@@a; If[PrimeQ[sum], AppendTo[lst,n]]; a=RotateLeft[a]; a[[step]]=sum]; lst

A268410 a(n) = a(n - 1) + a(n - 2) + a(n - 3) for n>2, a(0)=5, a(1)=7, a(2)=9.

Original entry on oeis.org

5, 7, 9, 21, 37, 67, 125, 229, 421, 775, 1425, 2621, 4821, 8867, 16309, 29997, 55173, 101479, 186649, 343301, 631429, 1161379, 2136109, 3928917, 7226405, 13291431, 24446753, 44964589, 82702773, 152114115, 279781477, 514598365, 946493957
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 04 2016

Keywords

Comments

Tribonacci sequence beginning 5, 7, 9.
In general, the ordinary generating function for the recurrence relation b(n) = b(n-1) + b(n-2) + b(n-3), with n>2 and b(0)=k, b(1)=m, b(2)=q, is (k + (m-k)*x + (q-m-k)*x^2)/(1 - x - x^2 - x^3).

Crossrefs

Cf. similar sequences with initial values (p,q,r): A000073 (0,0,1), A081172 (1,1,0), A001590 (0,1,0; also 1,2,3), A214899 (2,1,2), A001644 (3,1,3), A145027 (2,3,4), A000213 (1,1,1), A141036 (2,1,1), A141523 (3,1,1), A214727 (1,2,2), A214825 (1,3,3), A214826 (1,4,4), A214827 (1,5,5), A214828 (1,6,6), A214829 (1,7,7), A214830 (1,8,8), A214831 (1,9,9).

Programs

  • GAP
    a:=[5,7,9];; for n in [4..40] do a[n]:=a[n-1]+a[n-2]+a[n-3]; od; a; # G. C. Greubel, Apr 23 2019
  • Magma
    I:=[5,7,9]; [n le 3 select I[n] else Self(n-1)+Self(n-2)+Self(n-3): n in [1..40]]; // Vincenzo Librandi, Feb 04 2016
    
  • Mathematica
    LinearRecurrence[{1, 1, 1}, {5, 7, 9}, 40]
    RecurrenceTable[{a[0]==5, a[1]==7, a[2]==9, a[n]==a[n-1]+a[n-2]+a[n-3]}, a, {n, 40}]
  • PARI
    my(x='x+O('x^40)); Vec((5+2*x-3*x^2)/(1-x-x^2-x^3)) \\ G. C. Greubel, Apr 23 2019
    
  • Sage
    ((5+2*x-3*x^2)/(1-x-x^2-x^3)).series(x, 40).coefficients(x, sparse=False) # G. C. Greubel, Apr 23 2019
    

Formula

G.f.: (5 + 2*x - 3*x^2)/(1 - x - x^2 - x^3).
a(n) = 3*K(n) - 4*T(n+1) + 8*T(n), where K(n) = A001644(n) and T(n) =A000073(n+1). - G. C. Greubel, Apr 23 2019

A230016 Indices of primes in the tribonacci-like sequence, A214825.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 10, 16, 17, 26, 32, 104, 109, 120, 133, 312, 546, 608, 2274, 2527, 2932, 4462, 4680, 6001, 7103, 17402, 17874, 20664, 26341, 27954, 32869, 36204, 41521, 49065, 64172, 66318, 196078
Offset: 1

Views

Author

Robert Price, Feb 22 2014

Keywords

Comments

a(39) > 2*10^5.

Crossrefs

Programs

  • Mathematica
    a={1,3,3}; Print[1];Print[2]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]

A230017 Prime terms in the tribonacci-like sequence, A214825.

Original entry on oeis.org

3, 3, 7, 13, 23, 43, 79, 491, 19009, 34963, 8422747, 326099713, 3699221592878859104602113553, 77867739062209443974741001359, 63460200981504216633346603450897, 174962190954783387911511685367053207
Offset: 1

Views

Author

Robert Price, Feb 22 2014

Keywords

Crossrefs

Programs

  • Mathematica
    a={1,3,3}; Print[3]; Print[3]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[3]]=sum]

A241661 Primes in A001630.

Original entry on oeis.org

2, 3, 23, 60217, 108412217573460833, 143003097309669584171480759
Offset: 1

Views

Author

Robert Price, Apr 26 2014

Keywords

Comments

a(7) is too large to display here. It has 206 digits and is the 722nd term in A001630.

Crossrefs

Programs

  • Mathematica
    a={0,0,1,2}; Print[2]; For[n=4, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[4]]=sum]

Extensions

a(1)=2 prepended and Mathematica program corrected by Robert Price, Sep 09 2014

A242316 Prime terms in the tribonacci-like sequence A214826.

Original entry on oeis.org

17, 103, 1764391, 8907752079422393063, 28959877095025359725108610631647478770525190687597954707985655095645523042346644747326776183477265033
Offset: 1

Views

Author

Robert Price, May 10 2014

Keywords

Comments

a(6) is too large to appear here, having 124 digits. It corresponds to A214826(467).

Crossrefs

Programs

  • Mathematica
    a={1,4,4}; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[3]]=sum]
    Select[LinearRecurrence[{1,1,1},{1,4,4},400],PrimeQ] (* Harvey P. Dale, Mar 17 2016 *)

A242325 Prime terms in the tribonacci-like sequence A214827.

Original entry on oeis.org

5, 5, 11, 37, 127, 233, 1451, 4909, 9029, 16607, 103333, 37314473023, 232180447061, 2657194941637, 13356042204482014297297131147848321, 4717604056747741831285902446873182186115052544834224581062711115537322612895948580479
Offset: 1

Views

Author

Robert Price, May 10 2014

Keywords

Comments

a(17) is too large to display here having 133 digits. It corresponds to A214827(501).

Crossrefs

Programs

  • Mathematica
    a={1,5,5}; Print[5]; Print[5]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[3]]=sum]
Previous Showing 41-50 of 52 results. Next