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A110934
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Difference between 3-almostprime(n) and 3-almostprime(n+2).
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0
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10, 8, 9, 8, 3, 14, 14, 3, 6, 7, 13, 14, 5, 4, 7, 6, 3, 16, 20, 7, 4, 6, 8, 9, 6, 3, 8, 8, 6, 13, 17, 10, 6, 6, 11, 11, 6, 6, 2, 3, 3, 8, 11, 6, 4, 7, 17, 17, 15, 18, 9, 6, 7, 6, 6, 3, 2, 10, 12, 6, 8, 7, 7, 7, 6, 7, 5, 3, 2, 5, 6, 20, 24, 8, 6, 7, 10, 8, 6, 10, 7
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| This is the 3-almost prime analogue of what A113784 is for semiprimes and what A031131 is for primes. The the minimum values in the sequence are 2 because we have, for example, the 3 consecutive 3-almost primes 170, 171, 172, so a(39) = A014612(41) - A014612(39) = 172 - 170 = 2. Equivalently, there are 2 consecutive 1 values of A114403 (3-almost prime gaps; first differences of A014612). This happens for elements of A113789 (numbers n such that n, n+1 and n+2 are 3-almost primes).
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FORMULA
| a(n) = A014612(n+2) - A014612(n).
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EXAMPLE
| a(1) = 10 because the difference between the first and third 3-almost primes is A014612(3) - A014612(1) = 18 - 8 = 10.
a(2) = A014612(4) - A014612(2) = 20 - 12 = 8.
a(3) = A014612(5) - A014612(3) = 27 - 18 = 9.
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CROSSREFS
| Cf. A014612, A031131, A067813, A113784, A113789, A114403.
Sequence in context: A128357 A024134 A180197 * A065691 A147974 A038310
Adjacent sequences: A110931 A110932 A110933 * A110935 A110936 A110937
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KEYWORD
| easy,nonn
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Jan 21 2006
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EXTENSIONS
| a(28) corrected by R. J. Mathar, Dec 22 2010
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