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 1-3 of 3 results.

A105759 Prime Fibonacci 6-step numbers, A001592.

Original entry on oeis.org

2, 13435170943, 26649774581, 610186256014622144673892607
Offset: 1

Views

Author

T. D. Noe, Apr 22 2005

Keywords

Comments

The next term has 196 digits. - Harvey P. Dale, Apr 23 2025

Links

Crossrefs

Cf. A105758 (indices of prime Fibonacci 6-step numbers).

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, s]], {n, 1000}]; lst
Select[LinearRecurrence[{1,1,1,1,1,1},{1,0,0,0,0,0},100],PrimeQ] (* Harvey P. Dale, Apr 23 2025 *)

A249635 Indices of prime Fibonacci 6-step numbers, A001592.

Original entry on oeis.org

7, 40, 41, 96, 664, 6095, 8419, 11471, 13690, 38835, 49832, 97152
Offset: 1

Views

Author

Robert Price, Nov 02 2014

Keywords

Comments

This sequence is similar to A105758 but uses the indexing scheme defined by A001592, whose indices start with 0.
a(13) > 3*10^5.

Links

Crossrefs

Cf. A001592, A105758.

Programs

  • Mathematica
    a = {0, 0, 0, 0, 0, 1}; For[n = 6, n ≤ 1000, n++, sum = Plus @@ a;
If[PrimeQ[sum], Print[n]]; a = RotateLeft[a]; a[[6]] = sum]

Formula

a(n) = A105758 (n) + 4.

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.
Showing 1-3 of 3 results.

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