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Smallest Fibonacci number with n prime factors when counted with multiplicity.
5

%I #14 Feb 03 2023 01:33:07

%S 2,21,8,6765,2584,144,832040,86267571272,46368,14930352,

%T 30960598847965113057878492344,4807526976,160500643816367088,

%U 498454011879264,16641027750620563662096,51680708854858323072,34507973060837282187130139035400899082304280

%N Smallest Fibonacci number with n prime factors when counted with multiplicity.

%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha108.htm">Fibonacci numbers (n = 1 to 100)</a>.

%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha109.htm">Fibonacci numbers (n = 101 to 200)</a>.

%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha110.htm">Fibonacci numbers (n = 201 to 300)</a>.

%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha111.htm">Fibonacci numbers (n = 301 to 400)</a>.

%H Hisanori Mishima, <a href="http://www.asahi-net.or.jp/~KC2H-MSM/mathland/matha1/matha112.htm">Fibonacci numbers (n = 401 to 480)</a>.

%F a(n) = A000045(A072396(n)). - _Alois P. Heinz_, Apr 10 2018

%e 21 is the 2nd term because 21 is the smallest Fibonacci number having 2 prime factors.

%Y Cf. A000045, A072396.

%Y Row n=1 of A303216.

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Jul 21 2002

%E a(17) from _Alois P. Heinz_, Apr 10 2018