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A192530 Index-list (modified) of the primes generated at A192583. 3
1, 2, 3, 3, 4, 5, 6, 7, 9, 11, 12, 13, 15, 16, 19, 22, 23, 24, 27, 28, 33, 34, 35, 39, 41, 48, 57, 61, 66, 72, 95, 102, 114, 117, 128, 143, 148, 184, 196, 227, 228, 266, 302, 325, 367, 417, 471, 606, 882, 916, 1071, 1539, 4305 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Besides the generated primes 2,5,11,13,17,..., the initial numbers 4,6,8 in A192583 are represented here by index of nearest lower prime.

LINKS

Table of n, a(n) for n=1..53.

EXAMPLE

A192583=(2,4,5,6,8,11,13,17,23,...).  a(1)=1 because the index of 2 is 1; a(2)=2 because, for term #2 of A192530, which is 4, the nearest prime <4 is 3, which has index 2; a(3)=3 because the index of 5 is 3.  ("Nearest prime down" for nonprimes is given by PrimePi in the Mathematica program.)

MATHEMATICA

start = {2, 4, 6, 8}; primes = Table[Prime[n], {n, 1, 10000}];

f[x_, y_] := If[MemberQ[primes, x*y + 1], x*y + 1]

b[x_] :=

  Block[{w = x},

   Select[Union[

     Flatten[AppendTo[w,

       Table[f[w[[i]], w[[j]]], {i, 1, Length[w]}, {j, 1, i}]]]], # <

      10000000 &]];

t = FixedPoint[b, start]  (* A192583 *)

PrimePi[t] (* A192530 Nonprimes 4, 6, 8 are represented by "next prime down". *)

CROSSREFS

Cf. A192583.

Sequence in context: A039732 A011876 A029036 * A281744 A026838 A182229

Adjacent sequences:  A192527 A192528 A192529 * A192531 A192532 A192533

KEYWORD

nonn,fini,full

AUTHOR

Clark Kimberling, Jul 04 2011

STATUS

approved

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Last modified August 7 16:00 EDT 2022. Contains 355994 sequences. (Running on oeis4.)