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A369464 Numbers for which there is no representation as a sum (p*q + p*r + q*r) with three odd primes p <= q <= r.

%I A369464 #8 Jan 24 2024 12:19:56
%S A369464 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,
%T A369464 26,28,29,30,31,32,33,34,35,36,37,38,40,41,42,43,44,45,46,47,48,49,50,
%U A369464 52,53,54,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,72,73,74,76,77,78,79,80,81,82,83,84,85,86,88
%N A369464 Numbers for which there is no representation as a sum (p*q + p*r + q*r) with three odd primes p <= q <= r.
%o A369464 (PARI)
%o A369464 isA369251(n) = if(3!=(n%4),0, my(v = [3,3], ip = #v, r); while(1, r = (n-(v[1]*v[2])) / (v[1]+v[2]); if(r < v[2], ip--, ip = #v; if(1==denominator(r) && isprime(r), return(1))); if(!ip, return(0)); v[ip] = nextprime(1+v[ip]); for(i=1+ip,#v,v[i]=v[i-1])));
%o A369464 isA369464(n) = !isA369251(n);
%Y A369464 Complement of A369251. Numbers not in A369252.
%Y A369464 Union of A004773 and A369056.
%Y A369464 Positions of 0's in A369054.
%Y A369464 Cf. A098700, A369248, A369249, A369463 (subsequences).
%K A369464 nonn
%O A369464 1,3
%A A369464 _Antti Karttunen_, Jan 24 2024