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A090869 Irregular primes whose indices are irregular primes of order one. +0
1
613, 877, 1117, 1721, 1753, 2153, 2557, 2671, 4349, 4943, 5039, 5179, 5443, 5641, 5939, 6037, 6827, 6997, 7591, 7853, 8069, 8209, 8527, 8669, 9221, 9311, 9377, 9859, 10729, 11149, 11353, 11503, 11933, 12211, 12413, 12743, 12923, 13001, 13037 (list; graph; listen)
OFFSET

1,1

COMMENT

The number of primes in this sequence is infinite.

EXAMPLE

37 is the first irregular prime, 613 is the 37-th irregular prime, i.e. iprime[iprime[1]] = 613, so 613 is a member.

PROGRAM

(PARI) \ Irregular prime index primes. Download the ir12mill2.txt file from this link into the gp working dir http://groups.yahoo.com/group/B2LCC/files/Bernoulli/ This was simplified from the table found at http://www.shokrollahi.com/amin/TAB.html#bernoulli ftp://ftp.reed.edu/pub/users/jpb/ Start a new PARI session. Default(histsize, 310443). Perform irp12mill2.txt to read in the file.

iprimetable(n) = \ run this only once to produce the iprime[] array { iprime = vector(310443); for (i = 1, n, iprime[i] = eval( Str("%", i)); ) }

ipips(n) = { for(x=1, n, y=iprime[iprime[x]]; \ ipips of order 1 print1(y", ")) }

CROSSREFS

Sequence in context: A159641 A100364 A142435 this_sequence A020372 A032657 A117503

Adjacent sequences: A090866 A090867 A090868 this_sequence A090870 A090871 A090872

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard (hillcino368(AT)gmail.com), Feb 12 2004

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Last modified November 27 22:38 EST 2009. Contains 167602 sequences.


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