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%I #11 Jan 17 2023 07:14:35
%S 21,504,39648,6930,12669125245488,471771076278370,
%T 32818036405994618064,71577732779401085355729600,
%U 204945946670840805166309694624676331385919836360545974559162291811394735721440
%N a(n) is the smallest Fibonacci n-step number with exactly n distinct prime factors.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/DistinctPrimeFactors.html">Distinct Prime Factors</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Fibonaccin-StepNumber.html">Fibonacci n-Step Number</a>
%e a(3) = 504, because 504 is a tribonacci number with 3 distinct prime factors {2, 3, 7} and this is the smallest such number.
%o (PARI) a(n) = my(v=vector(n+1), x=1, y=n+1); v[1]=v[y]=1; while(omega(v[x])!=n, y=x; x=x%(n+1)+1; v[x]=2*v[y]-v[x]); v[x]; \\ _Jinyuan Wang_, Jan 16 2023
%Y Cf. A001221, A060319, A359848, A359849, A359853.
%K nonn
%O 2,1
%A _Ilya Gutkovskiy_, Jan 15 2023
%E a(10) from _Jinyuan Wang_, Jan 16 2023