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Semiprimes that are not the sum of 3 pentagonal numbers.
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%I #9 Jun 13 2016 19:36:26

%S 4,9,21,26,33,38,55,65,77,111,142,159,166,183,205,217,226,265,346,371,

%T 395,417,453,551,573,597,655,681,843,905,951,985,1059,1165,1441,1563,

%U 2033,2073,2126,2361,2487,2841,2991,3831,4061,4601,8691,10911

%N Semiprimes that are not the sum of 3 pentagonal numbers.

%C Semiprime analog of A117065.

%t v = #*(3*#-1)/2& @ Range[0, 90]; Select[ Complement[ Range[0, 11000], Union[Total /@ Tuples[{v, v, v}]]], PrimeOmega[#] == 2 &] (* _Giovanni Resta_, Jun 13 2016 *)

%Y A001358 intersect A003679.

%Y Cf. A001358, A003679, A117065.

%K fini,full,nonn

%O 1,1

%A _Jonathan Vos Post_, Aug 06 2006

%E Missing a(39) = 2126 from _Giovanni Resta_, Jun 13 2016