OFFSET
1,2
COMMENTS
All prime terms of A001606 (i.e., terms in A001606 that are not nontrivial powers of 2) are terms of this sequence.
Conjecture: all terms are of the form 2^k*p for k >= 0 and p prime.
It is unknown whether 1816 is a term (the smallest number for which membership in the sequence is unknown); it depends on whether Lucas(1816)/47 is a semiprime or not. The following composite numbers are terms of the sequence: 3106, 3928, 4006, 5414, 5498, 14318, 20578. - Chai Wah Wu, Jan 03 2020
LINKS
MATHEMATICA
Select[Range[100], DivisorSigma[0, #]==DivisorSigma[0, LucasL[#]]&] (* Metin Sariyar, Jan 03 2020 *)
PROG
(PARI) for(k=1, 320, if(numdiv(k)==numdiv(fibonacci(k+1)+fibonacci(k-1)), print1(k, ", "))) \\ Hugo Pfoertner, Jan 03 2020
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Chai Wah Wu, Dec 31 2019
STATUS
approved