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A071683
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Nonprimes which are the average of two consecutive Fibonacci numbers.
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0
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1, 4, 72, 305, 1292, 5473, 23184, 98209, 416020, 1762289, 7465176, 31622993, 133957148, 567451585, 2403763488, 10182505537, 43133785636, 182717648081, 774004377960, 3278735159921, 13888945017644, 58834515230497
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Prove that 17 is the only prime which is the average of two consecutive Fibonacci numbers.
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MATHEMATICA
| f[n_] := Fibonacci[n]; a = Select[ Range[70], IntegerQ[(f[ # ] + f[ # + 1])/2] && !PrimeQ[(f[ # ] + f[ # + 1])/2] &]; (f[a] + f[a + 1])/2
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CROSSREFS
| Cf. A018252, A000045.
Sequence in context: A077112 A203537 A095385 * A192826 A190398 A003752
Adjacent sequences: A071680 A071681 A071682 * A071684 A071685 A071686
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KEYWORD
| nonn
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AUTHOR
| G. L. Honaker, Jr. (honak3r(AT)gmail.com), Jun 22 2002
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Jun 27 2002
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