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%I #13 Jul 25 2022 01:12:12
%S 71,101,109,151,181,191,229,233,239,241,269,283,311,349,367,373,379,
%T 409,419,433,439,461,463,467,479,487,491,569,571,593,599,601,607,643,
%U 647,653,659,683,727,733,739,743,751,757,811,821,823,827,829,857,877,881
%N Primes missing from the tree generated at A234960.
%C According to the conjecture at A234961, the limiting relative density of these primes is 1.
%H Clark Kimberling, <a href="/A234962/b234962.txt">Table of n, a(n) for n = 1..7000</a>
%t t = NestList[DeleteDuplicates[Flatten[Map[{#, NextPrime[2 #, -1], NextPrime[2 #, 1]} &, #]]] &, {2}, 12]; Complement[Map[Prime, Range[PrimePi[Last[#]]]], #] &[Last[t]] (* _Peter J. C. Moses_, Dec 30 2013 *)
%o (Python)
%o from sympy import prevprime, nextprime, primerange
%o def aupto(limit):
%o reach, expand = {2}, [2]
%o while True:
%o newreach = set()
%o while len(expand) > 0:
%o p = expand.pop()
%o for q in prevprime(2*p), nextprime(2*p):
%o if q not in reach:
%o newreach.add(q)
%o reach |= newreach
%o expand = list(newreach)
%o if prevprime(2*min(expand)) > limit:
%o in_tree = set(r for r in reach if r <= limit)
%o return sorted(set(primerange(1, limit+1)) - in_tree)
%o print(aupto(881)) # _Michael S. Branicky_, Jul 24 2022
%Y Cf. A234960, A234961.
%K nonn
%O 1,1
%A _Clark Kimberling_, Jan 01 2014
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