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Non-semiprime numbers of order 2.
2

%I #13 Jul 23 2024 15:04:15

%S 1,2,3,7,11,12,17,18,19,24,27,28,29,30,36,37,42,43,44,45,47,48,54,56,

%T 61,63,64,66,67,68,71,72,75,78,79,80,83,89,90,92,97,98,100,101,102,

%U 104,105,107,108,110,112,114,116,117,120,125,126,131,132,135,137,144,147,148

%N Non-semiprime numbers of order 2.

%C Non-semiprimes with non-semiprime subscripts (or indices).

%H Chai Wah Wu, <a href="/A176363/b176363.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A100959(A100959(n)).

%p A100959 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if numtheory[bigomega](a) <> 2 then return a; end if; end do end if; end proc: A176363 := proc(n) A100959(A100959(n)) ; end proc: seq(A176363(n),n=1..80) ; # _R. J. Mathar_, Apr 25 2010

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Apr 16 2010

%E Corrected (66 inserted) _R. J. Mathar_, Apr 25 2010