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%I #6 Apr 14 2021 18:16:05
%S 4,14,26,38,46,62,74,77,86,94,95,106,121,122,134,143,146,158,161,166,
%T 178,185,194,203,206,218,221,226,254,262,278,302,314,321,326,329,334,
%U 339,341,346,362,365,371,381,386,395,398,422,437,446,451,458,466,471
%N Semiprimes that are not Chen semiprimes A175634.
%C Non-Chen semiprimes: semiprimes m such that m+4 is neither a prime or a semiprime.
%o (Python)
%o from sympy.ntheory.factor_ import primeomega, isprime
%o def issemiprime(n): return primeomega(n) == 2
%o def ok(n): return issemiprime(n) and not (issemiprime(n+4) or isprime(n+4))
%o print(list(filter(ok, range(1, 472)))) # _Michael S. Branicky_, Apr 14 2021
%K nonn
%O 1,1
%A _Juri-Stepan Gerasimov_, Aug 08 2010
%E Corrected (234 replaced by 254, 471 inserted) by _R. J. Mathar_, Aug 10 2010