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A234962 Primes missing from the tree generated at A234960. 3
71, 101, 109, 151, 181, 191, 229, 233, 239, 241, 269, 283, 311, 349, 367, 373, 379, 409, 419, 433, 439, 461, 463, 467, 479, 487, 491, 569, 571, 593, 599, 601, 607, 643, 647, 653, 659, 683, 727, 733, 739, 743, 751, 757, 811, 821, 823, 827, 829, 857, 877, 881 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
According to the conjecture at A234961, the limiting relative density of these primes is 1.
LINKS
MATHEMATICA
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 *)
PROG
(Python)
from sympy import prevprime, nextprime, primerange
def aupto(limit):
reach, expand = {2}, [2]
while True:
newreach = set()
while len(expand) > 0:
p = expand.pop()
for q in prevprime(2*p), nextprime(2*p):
if q not in reach:
newreach.add(q)
reach |= newreach
expand = list(newreach)
if prevprime(2*min(expand)) > limit:
in_tree = set(r for r in reach if r <= limit)
return sorted(set(primerange(1, limit+1)) - in_tree)
print(aupto(881)) # Michael S. Branicky, Jul 24 2022
CROSSREFS
Sequence in context: A155953 A247200 A288907 * A166252 A339466 A339463
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 01 2014
STATUS
approved

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Last modified June 25 10:55 EDT 2024. Contains 373701 sequences. (Running on oeis4.)