The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A206097 Fibonacci numbers F that are squarefree semiprimes such that F+2 or F-2 is also a squarefree semiprime. 0
 55, 4181, 17711, 121393, 5702887 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(6) > Fibonacci(1500), if it exists. - Amiram Eldar, Aug 01 2024 LINKS Table of n, a(n) for n=1..5. EXAMPLE 55 = Fibonacci(10) is a term because 55 = 5 * 11 and 55 + 2 = 57 = 3 * 19 are both squarefree semiprimes. 4181 = Fibonacci(19) is a term because 4181 = 37 * 113 and 4181 + 2 = 4183 = 47 * 89 are both squarefree semiprimes. MATHEMATICA Select[Fibonacci[Range[300]], Last/@FactorInteger[#]=={1, 1} && (Last/@FactorInteger[#+2]=={1, 1} || Last/@FactorInteger[#-2]=={1, 1})&] CROSSREFS Subsequence of A000045, A006881 and A053409. Cf. A072381. Sequence in context: A060077 A035323 A250833 * A103918 A013537 A056567 Adjacent sequences: A206094 A206095 A206096 * A206098 A206099 A206100 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Feb 03 2012 EXTENSIONS Name corrected by Amiram Eldar, Aug 01 2024 STATUS approved

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.

Last modified September 17 12:06 EDT 2024. Contains 375987 sequences. (Running on oeis4.)