A109068 Products of two successive primes that can be partitioned in sum of three distinct primes which contain the prime divisors.

15, 35, 77, 221, 899, 1517, 2021, 5183, 8633, 11663, 23707, 27221, 36863, 41989, 47053, 57599, 60491, 77837, 111547, 164009, 233273, 324899, 372091, 416021, 471953, 522713, 568507, 608351, 665831, 680621

Offset: 1

Author

Giovanni Teofilatto, Aug 17 2005

Keywords

• nonn

Comments

Largest prime of sum of three primes are primes of the form p*q - p - q, where p and q are two successive primes (A096345).

Examples

			a(1) = 15 because 15 = 3+5+7 with 3*5 =15;
a(2) = 35 because 35 = 5+7+23 with 5*7=35;
a(3) = 77 because 77 = 7+11+59 with 7*11=77;
a(4) = 221 because 221= 13+17+191 with 13*17=221
		

Crossrefs

Cf. A096345.

Programs

PARI

lista(nn) = {for (n=1, nn, p = prime(n); q = prime(n+1); prd = p*q; if (isprime(prd - p - q), print1(prd, ", ")););} \\ Michel Marcus, Jun 03 2013

Formula

a(n) = A096345(n) - A001043(n).

Extensions

More terms from Michel Marcus, Jun 03 2013