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%I #7 Feb 06 2019 23:48:02
%S 1,4,6,8,9,12,13,16,17,19,20,23,24,25,27,28,31,33,34,36,37,38,41,42,
%T 44,47,48,50,52,53,54,56,57,58,59,63,66,68,69,70,71,72,73,75,77,78,81,
%U 82,83,84,85,88,90,91,92,94,96,98,99,102,103,104,107,110,111,112,113,114
%N Indices of nonprime numbers in the products of two noncomposite numbers.
%C The positions of nonprime numbers in A037143.
%C The nonprime numbers A018252 which are not in A037143 do not contribute to the sequence and have no index of this kind. - _R. J. Mathar_, May 01 2010
%p From _R. J. Mathar_, May 01 2010: (Start)
%p A037143 := 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:
%p A018252 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; end do: end if; end proc:
%p A176539 := proc(n) npr := A018252(n) ; for a from 1 do if A037143(a) = npr then return a ; elif A037143(a) > npr then return ; end if; end do: end proc: seq(A176539(n),n=1..220) ; (End)
%Y Cf. A018252.
%K nonn
%O 1,2
%A _Juri-Stepan Gerasimov_, Apr 19 2010
%E Corrected (70 inserted) by _R. J. Mathar_, May 01 2010
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