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A067526
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Numbers n such that n - 2^k is a prime or 1 for all k satisfying 0 < k, 2^k < n.
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5
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OFFSET
| 1,1
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COMMENTS
| Is the sequence finite?
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EXAMPLE
| 45 belongs to this sequence as 45- 2, 45-4, 45-8, 45-16, 45-32 etc. i.e. 43, 41,37,29 and 13 are all primes.
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MATHEMATICA
| f[n_] := Block[{k = 1}, While[2^k < n, k++ ]; k--; k]; Do[ a = Table[n - 2^k, {k, 1, f[n]} ]; If[ a[[ -1]] == 1, a = Drop[a, -1]]; If[ Union[ PrimeQ[a]] == {True}, Print[n]], {n, 5, 10^7, 2} ]
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CROSSREFS
| Cf. A039669 (n-2^k is prime).
Sequence in context: A082922 A036971 A000702 * A101760 A165713 A105148
Adjacent sequences: A067523 A067524 A067525 * A067527 A067528 A067529
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KEYWORD
| nonn,hard,more
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 17 2002
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 18 2002
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