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A140434
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Number of new visible points created at each step in an n X n grid.
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6
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1, 2, 4, 4, 8, 4, 12, 8, 12, 8, 20, 8, 24, 12, 16, 16, 32, 12, 36, 16, 24, 20, 44, 16, 40, 24, 36, 24, 56, 16, 60, 32, 40, 32, 48, 24, 72, 36, 48, 32, 80, 24, 84, 40, 48, 44, 92, 32, 84, 40, 64, 48, 104, 36, 80, 48, 72, 56, 116, 32, 120
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Equals row sums of triangle A143467 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 17 2008]
Equals first difference row of A018805: (1, 3, 7, 11, 19, 23, 35,...). [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Aug 17 2008]
a(n) is the number of rationals p/q such that |p|+|q|=n. - Geoffrey Critzer, Oct 11 2011
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MATHEMATICA
| f[n_] := FoldList[Plus, 1, 2 Array[EulerPhi, n, 2]] - Most[Flatten[ Append[{0}, FoldList[Plus, 1, 2 Array[EulerPhi, n, 2]]]]]
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CROSSREFS
| Cf. A018805, A100613, A140435.
Sequence in context: A162943 A131136 A117973 * A107748 A005884 A079890
Adjacent sequences: A140431 A140432 A140433 * A140435 A140436 A140437
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KEYWORD
| nonn
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AUTHOR
| Gregg Whisler (gkwhisler(AT)msn.com), Jun 25 2008, Jun 28 2008
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