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a(n) is the index of the smallest tetranacci number (A000078) with exactly n distinct prime factors.
4

%I #10 Jan 18 2023 02:21:48

%S 3,5,8,15,20,30,53,60,80,89,130,252

%N a(n) is the index of the smallest tetranacci number (A000078) 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/TetranacciNumber.html">Tetranacci Number</a>

%Y Cf. A000078, A001221, A060320, A359849, A359850.

%K nonn,more

%O 0,1

%A _Ilya Gutkovskiy_, Jan 15 2023

%E a(11) from _Daniel Suteu_, Jan 17 2023