A062291 Primes p = prime(k) such that k*p - 1 is also a prime.

3, 19, 37, 43, 61, 113, 251, 317, 359, 409, 463, 491, 557, 601, 683, 827, 863, 941, 1061, 1097, 1109, 1213, 1283, 1291, 1399, 1423, 1481, 1583, 1657, 1693, 1699, 1811, 2069, 2267, 2297, 2531, 2687, 2741, 2851, 3011, 3181, 3271, 3323, 3331, 3347, 3373

Offset: 1

Author

Jason Earls, Jul 02 2001

Keywords

• easy
• nonn

Examples

			19 is in the sequence because 19 is the 8th prime and 8*19 - 1 = 151 is a prime.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Programs

Mathematica

Select[ Prime[ Range[ 500 ] ], PrimeQ[ # PrimePi[ # ]-1 ]& ]

PARI

for(n=1,200, if(isprime(n*prime(n)-1),print(prime(n))))

PARI

{ n=k=0; forprime (p=2, 5*10^5, k++; if (isprime(k*p - 1), write("b062291.txt", n++, " ", p); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 04 2009

Extensions

More terms from Harvey P. Dale, Jul 05 2001