The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A147956 All positive integers that are not multiples of any Fibonacci numbers >= 2. 2

%I #17 Jul 15 2022 13:53:00

%S 1,7,11,17,19,23,29,31,37,41,43,47,49,53,59,61,67,71,73,77,79,83,97,

%T 101,103,107,109,113,119,121,127,131,133,137,139,149,151,157,161,163,

%U 167,173,179,181,187,191,193,197,199,203,209,211,217,223,227,229,239,241

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

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

%H Amiram Eldar, <a href="/A147956/b147956.txt">Table of n, a(n) for n = 1..10000</a>

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

%p q:= n-> not ormap(d-> (t-> issqr(t+4) or issqr(t-4)

%p )(5*d^2), numtheory[divisors](n) minus {1}):

%p select(q, [$1..250])[]; # _Alois P. Heinz_, Jul 15 2022

%t 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 *)

%o (PARI) isfib1(n) = if (n>1, my(k=n^2); k+=(k+1)<<2; (issquare(k) || issquare(k-8)));

%o isok(k) = fordiv(k, d, if (isfib1(d), return(0))); 1; \\ _Michel Marcus_, Jul 15 2022

%Y Cf. A092579.

%K nonn

%O 1,2

%A _Leroy Quet_, Nov 17 2008

%E Extended by _Ray Chandler_, Nov 24 2008

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 5 08:12 EDT 2024. Contains 373102 sequences. (Running on oeis4.)