A124684 Primes of the form (p*q - 2)/5 where p and q are successive primes.

229, 1153, 14149, 15013, 189733, 214657, 253573, 350593, 514561, 522289, 725041, 853669, 1304581, 1453681, 2027569, 2183281, 2212453, 2469637, 3238513, 4166017, 4331941, 4467013, 5234689, 5510371, 5992933, 6102913, 8100097, 8130673

Offset

1,1

Comments

These numbers times 5 are semiprimes.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

31*37 = 1147, 1147-2 = 1145, 1145/5 = 229 is a term.

Mathematica

Select[(Times @@@ Partition[Prime[Range[1000]], 2, 1] - 2) / 5, PrimeQ] (* Amiram Eldar, May 26 2024 *)

Prog

(PARI) g(n, p=5) = { for(x=1, n, y=prime(x)*prime(x+1)-2; if(y%p==0, if(isprime(y/p), print1(y/p, ", ")))) }

Crossrefs

Cf. A123921.

Sequence in context: A142608 A210514 A142665 * A379429 A332740 A178673

Adjacent sequences: A124681 A124682 A124683 * A124685 A124686 A124687

Keyword

easy,nonn

Author

Cino Hilliard, Dec 27 2006

Status

approved