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 A107390 Composite Fibonacci sequence: each term is the composite with index equal to the sum of the previous two terms. 0
 4, 6, 18, 36, 76, 147, 285, 532, 984, 1795, 3237, 5793, 10293, 18168, 31887, 55709, 96926, 167972, 290136, 499615, 857947, 1469576, 2511369, 4282663, 7289002, 12383250, 21002336, 35564859, 60136917, 101547211, 171253466, 288461204 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS What is the value of lim_{n -> infinity} a(n)/a(n+1)? - Ryan Propper, Jan 11 2007 LINKS FORMULA a(n) = A002808(a(n-1) + a(n-2)); a(1)=4, a(2)=6. EXAMPLE a(5) = A002808(18 + 36) = A002808(54) = 76. MATHEMATICA Composite[n_Integer] := FixedPoint[n + PrimePi[ # ] + 1 &, n + PrimePi[n] + 1]; a = 4; b = 6; Do[c = Composite[a + b]; Print[c]; a = b; b = c, {n, 100}] (* Ryan Propper, Jan 11 2007 *) CROSSREFS Cf. A002808, A000045, A107327. Sequence in context: A218898 A088810 A005199 * A051253 A175955 A303526 Adjacent sequences:  A107387 A107388 A107389 * A107391 A107392 A107393 KEYWORD nonn,easy AUTHOR Christopher M. Tomaszewski (cmt1288(AT)comcast.net), May 24 2005 EXTENSIONS More terms from Ryan Propper, Jan 11 2007 STATUS approved

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Last modified August 5 08:27 EDT 2021. Contains 346464 sequences. (Running on oeis4.)