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

3, 5, 7, 9, 13

Offset

1,1

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.

Links

Table of n, a(n) for n=1..5.

Example

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.

Prog

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

Crossrefs

Cf. A002110, A007504, A008578, A014284.

Sequence in context: A096231 A362133 A100432 * A145341 A121388 A161700

Adjacent sequences: A261030 A261031 A261032 * A261034 A261035 A261036

Keyword

nonn,more

Author

Altug Alkan, Nov 18 2015

Status

approved