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.

A147956 All positive integers that are not multiples of any Fibonacci numbers >= 2.

Original entry on oeis.org

1, 7, 11, 17, 19, 23, 29, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 73, 77, 79, 83, 97, 101, 103, 107, 109, 113, 119, 121, 127, 131, 133, 137, 139, 149, 151, 157, 161, 163, 167, 173, 179, 181, 187, 191, 193, 197, 199, 203, 209, 211, 217, 223, 227, 229, 239, 241
Offset: 1

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Author

Leroy Quet, Nov 17 2008

Keywords

Comments

This sequence contains a 1 and all terms of sequence A092579 that are not prime Fibonacci numbers.

Examples

			77 has the divisors 1,7,11,77. None of these divisors is a Fibonacci number >= 2. So 77 is included in the sequence.
		

Crossrefs

Cf. A092579.

Programs

  • Maple
    q:= n-> not ormap(d-> (t-> issqr(t+4) or issqr(t-4)
            )(5*d^2), numtheory[divisors](n) minus {1}):
    select(q, [$1..250])[];  # Alois P. Heinz, Jul 15 2022
  • Mathematica
    fibQ[n_] := IntegerQ @ Sqrt[5 n^2 - 4] || IntegerQ @ Sqrt[5 n^2 + 4]; aQ[n_] := !AnyTrue[Rest[Divisors[n]], fibQ]; Select[Range[250], aQ] (* Amiram Eldar, Oct 06 2019 *)
  • PARI
    isfib1(n) = if (n>1, my(k=n^2); k+=(k+1)<<2; (issquare(k) || issquare(k-8)));
    isok(k) = fordiv(k, d, if (isfib1(d), return(0))); 1; \\ Michel Marcus, Jul 15 2022

Extensions

Extended by Ray Chandler, Nov 24 2008