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 51-54 of 54 results.

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]

A247028 Primes in tetranacci sequence A001631.

Original entry on oeis.org

2, 7, 193, 19079, 1823013184807, 324494495853101147203936847, 16085434555484907108254435283952049, 255525859571903290673264616283734506003204622439226993660213169027169
Offset: 1

Views

Author

Robert Price, Sep 09 2014

Keywords

Comments

a(9) is too large to display here. It has 160 digits and is the 564th term in A001631.

Crossrefs

Cf. A001590, A001631, A100683, A231574, A231575, A232543, A214899, A020992, A233554. A214727, A234696, A141523, A235862,A214825, A235873, A001630, A241660, A247027.

Programs

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

A247946 Primes in the tetranacci sequence A000288.

Original entry on oeis.org

7, 13, 181, 349, 673, 1297, 34513, 90799453, 175021573, 4657290577, 17304140641, 1131469145856472270556751793, 1544310310927991136025089626209, 1442398599584422734286432395814518441223501, 18598135820391234761502881488353916158281807617671450769
Offset: 1

Views

Author

Robert Price, Sep 27 2014

Keywords

Comments

a(16) is too large to display here. It has 63 digits and is the 221st term in A000288.

Crossrefs

Cf. A001590, A001631, A100683, A231574, A231575, A232543, A214899, A020992, A233554, A214727, A234696, A141523, A235862, A214825, A235873, A001630, A241660, A247027, A000288, A247561.

Programs

  • Mathematica
    a={1,1,1,1}; For[n=4, n<=1000, n++, sum=Plus@@a; If[PrimeQ[sum], Print[sum]]; a=RotateLeft[a]; a[[4]]=sum]
Select[LinearRecurrence[{1,1,1,1},{1,1,1,1},300],PrimeQ] (* Harvey P. Dale, Jan 15 2015 *)

A385717 a(n) = a(n-1) + a(n-2) + a(n-3), with a(1) = 4, a(2) = 13, a(3) = 42.

Original entry on oeis.org

4, 13, 42, 59, 114, 215, 388, 717, 1320, 2425, 4462, 8207, 15094, 27763, 51064, 93921, 172748, 317733, 584402, 1074883, 1977018, 3636303, 6688204, 12301525, 22626032, 41615761, 76543318, 140785111, 258944190, 476272619
Offset: 1

Views

Author

Greg Dresden and Jiarui Zhou, Jul 07 2025

Keywords

Comments

For n >= 3, a(n) is the number of ways to tile this shape of length n with 1 X 1 squares, 1 X 2 dominos, and 1 X 3 trominos:
_
||_|_______
|||_|||_|||
|||
As an example, here is one of the a(8) = 717 ways to tile this shape of length 8:
_
| ||_________
|| | ||_|___|
|||

Links

Crossrefs

Cf. A100683, A354080.

Programs

  • Mathematica
    LinearRecurrence[{1, 1, 1}, {4, 13, 42}, 30]

Formula

a(n) = 9*A354080(n-2) + 2*A100683(n) for n >= 2.
G.f.: x*(4 + 9*x + 25*x^2)/(1 - x - x^2 - x^3). - Stefano Spezia, Jul 08 2025
Previous Showing 51-54 of 54 results.

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

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