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.

A095080 Fibeven primes, i.e., primes p whose Zeckendorf-expansion A014417(p) ends with zero.

Original entry on oeis.org

2, 3, 5, 7, 11, 13, 23, 29, 31, 37, 41, 47, 71, 73, 79, 83, 89, 97, 107, 109, 113, 131, 139, 149, 151, 157, 167, 173, 181, 191, 193, 199, 223, 227, 233, 241, 251, 257, 269, 277, 283, 293, 311, 317, 337, 353, 359, 367, 379, 397, 401, 409, 419, 421
Offset: 1

Views

Author

Antti Karttunen, Jun 01 2004

Keywords

Crossrefs

Intersection of A000040 and A022342. Union of A095082 and A095087. Cf. A095060, A095081.

Programs

  • Maple
    F:= combinat[fibonacci]:
    b:= proc(n) option remember; local j;
          if n=0 then 0
        else for j from 2 while F(j+1)<=n do od;
             b(n-F(j))+2^(j-2)
          fi
        end:
    a:= proc(n) option remember; local p;
          p:= `if`(n=1, 1, a(n-1));
          do p:= nextprime(p);
             if b(p)::even then break fi
          od; p
        end:
    seq(a(n), n=1..100);  # Alois P. Heinz, Mar 27 2016
  • Mathematica
    F = Fibonacci;
    b[n_] := b[n] = Module[{j},
         If[n == 0, 0, For[j = 2, F[j + 1] <= n, j++];
         b[n - F[j]] + 2^(j - 2)]];
    a[n_] := a[n] = Module[{p},
         p = If[n == 1, 1, a[n - 1]]; While[True,
         p = NextPrime[p]; If[ EvenQ[b[p]], Break[]]]; p];
    Array[a, 100] (* Jean-François Alcover, Jul 01 2021, after Alois P. Heinz *)
  • Python
    from sympy import fibonacci, primerange
    def a(n):
        k=0
        x=0
        while n>0:
            k=0
            while fibonacci(k)<=n: k+=1
            x+=10**(k - 3)
            n-=fibonacci(k - 1)
        return x
    def ok(n):
        return str(a(n))[-1]=="0"
    print([n for n in primerange(1, 1001) if ok(n)]) # Indranil Ghosh, Jun 07 2017