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A130451
Number of divisors of A123193(n).
2
1, 2, 2, 3, 2, 2, 3, 2, 2, 5, 2, 2, 2, 8, 3, 2, 8, 2, 2, 8, 2, 8, 2, 2, 3, 2, 8, 8, 2, 2, 8, 2, 8, 2, 2, 8, 2, 5, 2, 8, 2, 2, 2, 8, 2, 8, 8, 2, 2, 8, 2, 8, 3, 2, 8, 8, 2, 8, 8, 2, 8, 2, 2, 2, 8, 8, 2, 2, 8, 2, 3, 8, 2, 8, 2, 2, 8, 8, 8, 8
OFFSET
1,2
FORMULA
a(n)=A000005(A123193(n)). - R. J. Mathar, Nov 16 2007
MAPLE
isFib := proc(n) local i ; for i from 1 do if combinat[fibonacci](i) > n then RETURN(false) ; elif combinat[fibonacci](i) = n then RETURN(true) ; fi ; od: end: A123193 := proc(n) option remember ; local nmin, k ; nmin := 1 : if n > 1 then nmin := A123193(n-1)+1 ; fi ; for k from nmin do if isFib( numtheory[tau](k) ) then RETURN(k) ; fi ; od: end: A130451 := proc(n) numtheory[tau](A123193(n)) ; end: seq(A130451(n), n=1..80) ; # R. J. Mathar, Nov 16 2007
MATHEMATICA
FibQ[n_] := IntegerQ[Sqrt[5 n^2 + 4]] || IntegerQ[Sqrt[5 n^2 - 4]];
Select[DivisorSigma[0, Range[250]], FibQ] (* Jean-François Alcover, Jan 27 2024 *)
CROSSREFS
Sequence in context: A218800 A062502 A141242 * A130285 A046027 A283671
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Aug 08 2007
EXTENSIONS
Corrected and extended by R. J. Mathar, Nov 16 2007
STATUS
approved