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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

Table of n, a(n) for n=1..32.

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 February 23 04:44 EST 2019. Contains 320411 sequences. (Running on oeis4.)