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.

A133247 Prime numbers p with property that no odd Fibonacci number is divisible by p.

Original entry on oeis.org

2, 17, 19, 23, 31, 53, 61, 79, 83, 107, 109, 137, 167, 173, 181, 197, 211, 227, 229, 241, 257, 271, 293, 317, 349, 379, 383, 409, 421, 439, 443, 467, 499, 503, 541, 571, 587, 593, 601, 617, 631, 647, 653, 683, 691, 739, 751, 769, 773, 797, 811, 827, 829, 857
Offset: 1

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Author

Tanya Khovanova, Oct 14 2007, Oct 17 2007, Nov 02 2007

Keywords

Comments

The Mathematica coding uses the fact that the Pisano period - the period with which a Fibonacci sequence (mod n) repeats itself is not more than 6n and the fact that the Fibonacci sequence starts with 0.
Subsequence of A133246 except for 2.
Primes not in A155916. - Robert Israel, Nov 20 2016

Crossrefs

Programs

  • Maple
    filter:= proc(p) local a,b,i;
      if not isprime(p) then return false fi;
      a:= 0: b:= 1;
    for i from 2 do
      a,b:= b, (a+b) mod p;
      if b = 0 then
        if i mod 3 <> 0 then return false
        elif a = 1 then return true
        fi
      fi
    od:
    end proc:
    select(filter, [2,seq(i,i=3..1000,2)]); # Robert Israel, Nov 20 2016
  • Mathematica
    Transpose[ Select[Table[{Prime[m], Select[Table[{n, Mod[Fibonacci[n], Prime[m]]}, {n, 6Prime[m] + 1}], Mod[ #[[1]], 3] != 0 && #[[2]] == 0 &]}, {m, 300}], #[[2]] == {} &]][[1]]