A093552 a(n) is the smallest number m such that m-k is product of k+1 primes for k=0,1,2,...,n.

2, 5, 47, 107, 71999, 392279, 305778479, 24405534719, 899133243623

Offset: 0

Author

Farideh Firoozbakht, Apr 14 2004

Keywords

• nonn
• more

Comments

Each term of this sequence is prime.

Examples

			a(5)=392279 because:
392279 is prime;
392279-1 = 2*196139;
392279-2 = 3*229*571;
392279-3 = 2*2*281*349;
392279-4 = 5*5*13*17*71;
392279-5 = 2*3*3*19*31*37;
392279 is the smallest number m such that m-k is product of k+1 primes for k=0,1,2,3,4 & 5.
		

Crossrefs

Cf. A072664, A072875, A086560.

Programs

Mathematica

Table[m = 1; While[Table[Plus @@ Last /@ FactorInteger[Prime[m] - k], {k, 0, n}] != Range[1, n + 1], m++]; Prime[m], {n, 0, 5}] (* Robert Price, Jun 09 2019 *)

Extensions

a(6) corrected by Mike Oakes, Jun 20 2012

a(7) from Zak Seidov, Apr 23 2017

a(8) from Giovanni Resta, Apr 27 2017