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A164510
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First differences of A071904 (Odd composite numbers).
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3
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6, 6, 4, 2, 6, 2, 4, 6, 4, 2, 4, 2, 6, 2, 4, 6, 2, 4, 4, 2, 4, 2, 2, 4, 6, 6, 4, 2, 2, 2, 2, 2, 4, 4, 2, 6, 2, 2, 2, 6, 2, 4, 2, 4, 4, 2, 4, 2, 6, 2, 2, 2, 6, 6, 2, 2, 2, 2, 4, 2, 2, 2, 2, 4, 6, 4, 2, 6, 2, 2, 2, 4, 2, 4, 2, 4, 2, 6, 2, 4, 6, 2, 2, 2, 4, 2, 2, 2, 2, 2, 4, 6, 4, 2, 2, 2, 2, 2, 4, 2, 4, 2, 2, 2, 6
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OFFSET
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1,1
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COMMENTS
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Are all terms <=6?
Yes, all terms are at most 6. For a value of 8, we have to have p, p+2, p+4 all prime, and this is possible only for p=3. As a result, 1 would have to be an odd composite number, which it is not. Therefore all terms are <=6. [From J. Lowell, Aug 17 2009]
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LINKS
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PROG
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(Python)
from sympy import primepi, isprime
m, k = n, primepi(n+1) + n + (n+1>>1)
while m != k:
m, k = k, primepi(k) + n + (k>>1)
for d in range(2, 7, 2):
if not isprime(m+d):
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CROSSREFS
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KEYWORD
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nonn,changed
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AUTHOR
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STATUS
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approved
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