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Search: id:A055458
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| A055458 |
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a(n) = smallest composite solution x to the equation Phi[x+2n] = Phi[x]+2n. |
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+0
7
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| 6, 12, 21, 24, 36, 45, 48, 39, 63, 72, 72, 95, 60, 57, 224, 84, 15, 135, 1058, 45, 301, 144, 95, 162, 63, 189, 69, 156, 161, 180, 69, 260, 150, 115, 204, 129, 400, 75, 180, 165, 35, 117, 476, 7105, 288, 195, 324, 620, 240, 81, 145, 153, 644, 309, 203
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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1. Sivaramakrishnan(1989) quotes Makowski who gave solutions for d = 2^a and d = 2*3^a. Compare also to A007694 and A049237. 2. Smallest prime solutions appear to be identical with A054906
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REFERENCES
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Sivaramakrishnan, R. (1989): Classical theory of Arithmetical Functions. Marcel Dekker, Inc., New York-Basel. Chapter V, Problem 20, page 113.
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EXAMPLE
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n = 19,d = 38, a(19) = 1058 because Phi[1058+38] = Phi[1096] = 544 = 506+38 = Phi[1058]+38; n = 100,d = 200,a(100) = 225, Phi[225+200] = Phi[425] = 320 = 120+200 = Phi[225]+200
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CROSSREFS
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Cf. A000010, A054906, A050472, A050473, A007694, A049237.
Sequence in context: A028611 A141808 A144187 this_sequence A144568 A078472 A005694
Adjacent sequences: A055455 A055456 A055457 this_sequence A055459 A055460 A055461
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jun 26 2000
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EXTENSIONS
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More terms from Michel ten Voorde (seqfan(AT)tenvoorde.org) Jun 14 2003
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