A261033 Values of n such that A002110(n) - A007504(n) - 1 is a prime number.

3, 5, 7, 9, 13

Offset: 1

Author

Altug Alkan, Nov 18 2015

Keywords

• nonn
• more

Comments

Values of n such that difference between product of first n+1 terms of A008578 and sum of first n+1 terms of A008578 is a prime number.

Initial primes of the form A002110(n) - A007504(n) - 1 are 19, 2281, 510451.

Examples

			a(1) = 3 because (2*3*5) - (2+3+5) - 1 = 19 is prime.
a(2) = 5 because (2*3*5*7*11) - (2+3+5+7+11) - 1 = 2281 is prime.
a(3) = 7 because (2*3*5*7*11*13*17) - (2+3+5+7+11+13+17) - 1 = 510451 is prime.
		

Crossrefs

Cf. A002110, A007504, A008578, A014284.

Programs

PARI

for(n=1, 1e5, if(ispseudoprime(prod(k=1, n, prime(k)) - sum(k=1, n, prime(k)) - 1), print1(n, ", ")));