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A082433
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a(n) = A072181(n) - p, where p is the largest prime < A072181(n) - 1.
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0
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3, 5, 7, 7, 11, 11, 11, 11, 13, 23, 17, 17, 17, 41, 191, 47, 31, 53, 53, 53, 31, 179, 61, 61, 337, 131, 523, 523, 419, 223, 223, 223, 223, 79, 3821, 3821, 3821, 23399, 21269, 21269, 3607
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OFFSET
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3,1
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COMMENTS
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Are all terms prime?
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LINKS
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EXAMPLE
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PROG
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(Python)
from sympy import factorint, isprime
def afindn(terms):
prev_factors, prevan, prevk, n = dict(), 1, None, 2
for n in range(2, terms+1):
n_factors, an = factorint(n), 1
for pi in set(prev_factors.keys()) | set(n_factors.keys()):
ei = prev_factors[pi] if pi in prev_factors else 1
fi = n_factors[pi] if pi in n_factors else 1
an *= pi**(ei*fi)
if n >= 3:
if an != prevan:
k = 3
while not isprime(an - k): k += 2
else:
k = prevk
print(k, end=", ")
prevk = k
prev_factors, prevan = factorint(an), an
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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