A057017 Product of first n composite numbers minus 1 is a prime.

1, 2, 3, 9, 12, 22, 26, 30, 34, 51, 54, 100, 125, 155, 168, 173, 220, 401, 494

Offset

1,2

Links

Table of n, a(n) for n=1..19.

Example

a(3) = 3 because 4*6*8-1 = 191 which is prime.

Mathematica

Composite[ n_Integer ] := (k = n + PrimePi[ n ] + 1; While[ k - PrimePi[ k ] - 1 != n, k++ ]; k); Do[ m = n; If[ PrimeQ[ Product[ Composite[ k ], {k, 1, n} ] - 1 ], Print[ n ] ], {n, 1, 1980} ]

Crossrefs

Cf. A053982.

Sequence in context: A048084 A350439 A067719 * A330298 A330242 A239859

Adjacent sequences: A057014 A057015 A057016 * A057018 A057019 A057020

Keyword

nonn

Author

Robert G. Wilson v, Apr 21 2001

Status

approved