A286125 Numbers n such that antisigma(n) divides Fibonacci(n).

3, 4, 8, 672, 720, 3960, 25056, 114912, 323928, 1064880, 3899880, 16758000, 59222400

Offset

1,1

Comments

a(14) > 10^9. - Giovanni Resta, May 06 2017

Links

Table of n, a(n) for n=1..13.

Example

F(8) = 21, 8*9/2 - sigma(8) = 21 and 21/21 = 1.

Maple

with(numtheory): with(combinat): P:=proc(q) local n; for n from 1 to q do
if n*(n+1)/2-sigma(n)>0 then if type(fibonacci(n)/(n*(n+1)/2-sigma(n)), integer) then print(n); fi; fi; od; end: P(10^6);

Mathematica

Select[Range[3, 150000], Divisible[Fibonacci@ #, # (# + 1)/2 - DivisorSigma[1, #]] &] (* or *)
Do[If[Divisible[Fibonacci@ #, # (# + 1)/2 - DivisorSigma[1, #]] &@ n, Print@ n], {n, 3, 150000}] (* Michael De Vlieger, May 03 2017, both after Robert G. Wilson v at A024816 *)

Crossrefs

Cf. A000045, A024816, A258748.

Sequence in context: A096847 A367131 A011993 * A180169 A154714 A001695

Adjacent sequences: A286122 A286123 A286124 * A286126 A286127 A286128

Keyword

nonn,more

Author

Paolo P. Lava, May 03 2017

Extensions

a(10)-a(12) from Robert G. Wilson v, May 06 2017

a(13) from Giovanni Resta, May 06 2017

Status

approved