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Numbers that set a new record for number of Fibonacci divisors.
4

%I #66 Sep 10 2024 11:04:16

%S 1,2,6,24,120,720,5040,55440,720720,12252240,232792560,6750984240,

%T 276790353840,12732356276640,523410559111440,24076885719126240,

%U 1131613628798933280,100713612963105061920,20042008979657907322080

%N Numbers that set a new record for number of Fibonacci divisors.

%C From _Donovan Johnson_, Jul 07 2009: (Start)

%C a(15) <= 598420745002080,

%C a(16) <= 36503665445126880,

%C a(17) <= 1131613628798933280,

%C a(18) <= 100713612963105061920. (End)

%C From _Robert Israel_, Sep 26 2019: (Start)

%C a(15) <= 523410559111440,

%C a(16) <= 24076885719126240. (End)

%C From _David A. Corneth_, Sep 27 2019: (Start)

%C a(19) <= 20042008979657907322080,

%C a(20) <= 4669788092260292406044640,

%C a(21) <= 1312210453925142166098543840,

%C a(22) <= 414821946023574034721351415840,

%C a(23) <= 116564966832624303756699747851040,

%C a(24) <= 37417354353272401505900619060183840,

%C a(25) <= 19494441618054921184574222530355780640,

%C a(26) <= 31132623264033709131765033380978181682080,

%C a(27) <= 67277598873576845433744237136293850614974880. (End)

%C From a(1) up to a(14), last known term, this sequence is equivalent to: a(n) is the smallest number that has exactly n Fibonacci divisors (A000045). The products of the new Fibonacci divisors that appear successively are in A349100. - _Bernard Schott_, Jul 15 2022

%D J. Earls, Red Zen, Lulu Press, NY, 2006, p. 105.

%H David A. Corneth, <a href="/A129655/a129655_1.gp.txt">Some actual values and some upper bounds on a(n), for n=1..134</a>

%H David A. Corneth, <a href="/A129655/a129655_2.gp.txt">PARI program</a>

%F a(n) <= A035105(n+1). - _Daniel Suteu_, Sep 27 2019

%e 5040 has 60 divisors with 7 of them being Fibonacci numbers, namely 1, 2, 3, 5, 8, 21 and 144.

%Y Cf. A000045, A005086, A035105, A349100.

%K nonn,more

%O 1,2

%A _Jason Earls_, May 19 2007

%E More terms from _Donovan Johnson_, Feb 26 2008

%E a(14) from _Donovan Johnson_, Jul 07 2009

%E a(15)-a(19) confirmed by _David A. Corneth_, Sep 06 2024