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%I #10 Nov 24 2022 16:39:40
%S 0,0,0,9,9,9,18,18,18,18,27,27,27,27,27,36,36,45,45,45,45,54,54,54,63,
%T 63,72,72,72,72,81,81,81,81,99,108,108,108,108,117,117,117,117,126,
%U 126,135,135,135,135,135,144,144,144,153,153,153,162,162,171,171
%N The n-th semiprime minus its sum of digits.
%C This is to semiprimes A001358 as A068395 is to primes A000040. As with A068395, this is always a multiple of 9, hence cannot be prime. But, as happens first for a(4), a(n) can be semiprime.
%F a(n) = A001358(n) - A007953(A001358(n)).
%e a(4) = 10 - 1 = 9.
%e a(5) = 14 - 5 = 9.
%p read("transforms") :
%p A206011 := proc(n)
%p s := A001358(n) ;
%p s -digsum(s) ;
%p end proc: # _R. J. Mathar_, Sep 14 2012
%t #-Total[IntegerDigits[#]]&/@Select[Range[200],PrimeOmega[#]==2&] (* _Harvey P. Dale_, Nov 24 2022 *)
%Y Cf. A000040, A001358, A007953, A068395.
%K nonn,easy,base
%O 1,4
%A _Jonathan Vos Post_, Feb 02 2012
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