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A073320 A073259(n)=3: the length of iteration transient leading to n-th composite number equals 3. 2
4, 5, 8, 9, 13, 16, 17, 18, 22, 23, 24, 27, 31, 35, 36, 40, 41, 46, 47, 56, 64, 69, 70, 71, 89, 90, 91, 92, 93, 94, 95, 103, 109, 110, 111, 112, 113, 146, 147, 161, 162, 163, 171, 172, 173, 174, 196, 240, 241, 242, 243, 261, 262, 263, 277, 438, 439, 440, 1137, 1138 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..60.

FORMULA

See Program.

EXAMPLE

The sequence is most probably complete. a(1)=4: the fixed point list from m=a(1) to composite[m] is: {4,7,9}, the length is 3; last term is a(64)=1142 with transient list {1142,1332,1360}.

MATHEMATICA

lfp[x_] := Length[FixedPointList[x+PrimePi[ # ]+1&, x]]-1 Do[s=lfp[n]; If[Equal[s, 3], Print[n]], {n, 1, 10000000}]

CROSSREFS

Cf. A002808, A073259.

Sequence in context: A316097 A206554 A267489 * A020668 A020934 A094004

Adjacent sequences:  A073317 A073318 A073319 * A073321 A073322 A073323

KEYWORD

fini,full,nonn

AUTHOR

Labos Elemer, Jul 29 2002

STATUS

approved

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Last modified October 24 04:33 EDT 2021. Contains 348217 sequences. (Running on oeis4.)