A177799 - OEIS

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A177799

Primes of the form prime(prime(n)) mod prime(n), sorted by increasing n.

2, 3, 2, 3, 19, 23, 29, 41, 2, 7, 13, 19, 23, 31, 71, 71, 73, 73, 79, 109, 137, 149, 197, 197, 257, 263, 263, 311, 349, 349, 337, 349, 383, 383, 421, 433, 23, 29, 23, 19, 17, 31, 71, 131, 139, 223, 263, 293, 293, 521, 557, 593, 613, 631, 823, 911, 919, 919, 947, 1109, 1427, 1487, 1483, 1613, 1693, 1913, 2131, 2203, 2381, 2659

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

This scans A004648(A000040(.)) = 1, 2, 1, 3, 9, 2, 8, 10,... , and discards composites.

LINKS

Table of n, a(n) for n=1..70.

EXAMPLE

a(1)=2 because (prime(prime(2))=5 mod prime(2)=3)=2=prime.

PROG

(PARI) s=[]; for(n=1, 3000, p=prime(prime(n))%prime(n); if(isprime(p), s=concat(s, p))); s \\ Colin Barker, Jun 28 2014

CROSSREFS