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 1-10 of 14 results. Next

A242324 Indices of primes in the tribonacci-like sequence A214827.

Original entry on oeis.org

1, 2, 3, 5, 7, 8, 11, 13, 14, 15, 18, 39, 42, 46, 128, 319, 501, 645, 749, 785, 924, 1786, 1810, 3032, 3053, 3913, 4444, 5611, 6290, 20526, 20850, 23431, 44281, 45981, 103816, 133938
Offset: 1

Views

Author

Robert Price, May 10 2014

Keywords

Comments

a(37) > 2*10^5.

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727, A081172, A214752, A141523,A214825, A235862, A214827.

Programs

  • Mathematica
    a={1,5,5}; Print[1];Print[2]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]

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

Cf. A001590, A100683, A231574, A231575, A232543, A214899, A020992, A233554. A214727, A234696, A141523, A235862,A214825, A235873, A214827, A242324.

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]

A214829 a(n) = a(n-1) + a(n-2) + a(n-3), with a(0) = 1, a(1) = a(2) = 7.

Original entry on oeis.org

1, 7, 7, 15, 29, 51, 95, 175, 321, 591, 1087, 1999, 3677, 6763, 12439, 22879, 42081, 77399, 142359, 261839, 481597, 885795, 1629231, 2996623, 5511649, 10137503, 18645775, 34294927, 63078205, 116018907, 213392039, 392489151, 721900097, 1327781287, 2442170535
Offset: 0

Views

Author

Abel Amene, Aug 07 2012

Keywords

Comments

See comments in A214727.

Links

Crossrefs

Cf. A000213, A000288, A000322, A000383, A060455, A136175, A141036, A141523, A214825, A214826, A214827, A214828, A214830, A214831.

Programs

  • GAP
    a:=[1,7,7];; 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+6*x-x^2)/(1-x-x^2-x^3) )); // G. C. Greubel, Apr 24 2019
  • Mathematica
    LinearRecurrence[{1,1,1}, {1,7,7}, 40] (* G. C. Greubel, Apr 24 2019 *)
  • PARI
    Vec((x^2-6*x-1)/(x^3+x^2+x-1) + O(x^40)) \\ Michel Marcus, Jun 04 2017
  • Sage
    ((1+6*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+6*x-x^2)/(1-x-x^2-x^3).
a(n) = -A000073(n) + 6*A000073(n+1) + A000073(n+2). - G. C. Greubel, Apr 24 2019

A243622 Indices of primes in A214829.

Original entry on oeis.org

1, 2, 4, 10, 11, 12, 13, 58, 63, 89, 132, 157, 426, 457, 506, 613, 1839, 1936, 2042, 2355, 3178, 3782, 8556, 8688, 22152, 23232, 44074, 71770, 222666
Offset: 1

Views

Author

Robert Price, Jun 07 2014

Keywords

Comments

a(30) > 222666.

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727, A081172, A214752, A141523,A214825, A235862, A214827, A214828.

Programs

  • Mathematica
    a={1,7,7}; Print["1"]; Print["2"]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]

Extensions

a(27) corrected by Robert Price, May 22 2019
a(29) from Robert Price, May 23 2019

A242576 Prime terms in A214828.

Original entry on oeis.org

13, 151, 277, 36313, 225949, 7129366889, 933784181621, 19397107178326126131136629644898891137047, 401151570474397232184569825031979125080583558010764826781295643008140597581801
Offset: 1

Views

Author

Robert Price, May 17 2014

Keywords

Comments

a(10) has 119 digits and thus is too large to display here. It corresponds to A214828(448).

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232543, A214899, A020992, A233554. A214727, A234696, A141523, A235862, A214825, A235873, A242324, A214827, A214828.

Programs

  • Mathematica
    a={1,6,6}; 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},{1,6,6},350],PrimeQ] (* Harvey P. Dale, Jul 21 2018 *)
  • PARI
    my(x='x+O('x^500)); select(isprime, Vec((1+5*x-x^2)/(1-x-x^2-x^3))) \\ Michel Marcus, Jun 16 2025

A243623 Prime terms in A214829.

Original entry on oeis.org

7, 29, 1087, 1999, 3677, 6763, 5487349608898607, 115507410616162687, 878001744429057971864287, 210582098197038415344728317608265501, 870277059555114378903885645581650740066907
Offset: 1

Views

Author

Robert Price, Jun 07 2014

Keywords

Comments

a(12) has 114 digits and thus is too large to display here. It corresponds to A214829(426).

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232543, A214899, A020992, A233554. A214727, A234696, A141523, A235862,A214825, A235873, A214827, A242324, A214827, A214828, A214829, A242572, A242576, A243622.

Programs

  • Maple
    f:= gfun:-rectoproc({a(n) = a(n-1) + a(n-2) + a(n-3), a(0) = 1, a(1) = 7, a(2) = 7},a(n),remember):
select(isprime, map(f, [$2..1000])); # Robert Israel, Sep 02 2024
  • Mathematica
    a={1,7,7}; Print["7"]; Print["7"]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[3]]=sum]

Extensions

7 inserted as a(1) by Robert Israel, Sep 02 2024

A242572 Indices of primes in A214828.

Original entry on oeis.org

3, 7, 8, 16, 19, 36, 44, 151, 292, 448, 467, 896, 1148, 1607, 1711, 1956, 2020, 6635, 14228, 25519, 43140, 74984, 77696, 137975
Offset: 1

Views

Author

Robert Price, May 17 2014

Keywords

Comments

a(25) > 2*10^5.

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727, A081172, A214752, A141523,A214825, A235862, A214827, A214828.

Programs

  • Mathematica
    a={1,6,6}; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]

A244001 Indices of primes in A214830.

Original entry on oeis.org

3, 7, 11, 20, 28, 63, 72, 79, 688, 795, 999, 2716, 13220, 15940, 17903, 26832, 28416, 33448, 117923
Offset: 1

Views

Author

Robert Price, Jun 17 2014

Keywords

Comments

a(20) > 2*10^5.

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727, A081172, A214752, A141523,A214825, A235862, A214827, A214828, A214829, A243622, A243623.

Programs

  • Mathematica
    a={1,8,8}; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]

A246517 Indices of primes in A141036.

Original entry on oeis.org

0, 5, 14, 26, 33, 222, 234, 482, 937, 1170, 1290, 1877, 1897, 3413, 6017, 9365, 47470, 48254, 97421, 102057, 119689, 132418, 192517, 194442
Offset: 1

Views

Author

Robert Price, Aug 28 2014

Keywords

Comments

a(25) > 2*10^5.
A141036(a(n)) = A246518(n).

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232542, A214899, A230607, A020992, A232498, A214727, A081172, A214752, A141523, A214825, A235862, A214827-A214829, A243622, A243623, A214831, A141036.
Cf. A049084.

Programs

  • Haskell
    a246517 n = a246517_list !! (n-1)
a246517_list = filter ((== 1) . a010051'' . a141036) [0..]
-- Reinhard Zumkeller, Sep 15 2014
  • Mathematica
    a={2,1,1}; Print[0]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[n]]; a=RotateLeft[a]; a[[3]]=sum]

A246518 Prime terms in A141036.

Original entry on oeis.org

2, 11, 2713, 4066709, 289593761, 30236674150891013353640837416685668536004108580572237299601, 45323907186142905348893078704293178796516046414129798590935901
Offset: 1

Views

Author

Robert Price, Aug 28 2014

Keywords

Comments

a(8) has 91 digits and thus is too large to display here. It corresponds to A141036(482).
a(n) = A141036(A246517(n)).

Links

Crossrefs

Cf. A001590, A100683, A231574, A231575, A232543, A214899, A020992, A233554. A214727, A234696, A141523, A235862, A214825, A235873, A242324, A214827-A214829, A242572, A242576, A243622, A244001, A214831, A244002, A141036, A246517.
Cf. A010051.

Programs

  • Haskell
    a246518 n = a246518_list !! (n-1)
a246518_list = filter ((== 1) . a010051'') $ a141036_list
-- Reinhard Zumkeller, Sep 15 2014
  • Mathematica
    a={2,1,1}; Print[2]; For[n=3, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[3]]=sum]
Showing 1-10 of 14 results. Next

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement.