A099161 Numbers m such that there is at least one k < prime(m+1) such that k*(prime(m)#)^2 - 1 and k*(prime(m)#)^2 + 1 are twin primes.

1, 2, 3, 4, 5, 10, 16, 18, 24, 31, 32, 35, 38, 51, 58, 71, 75, 78

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Example

2 is a term because the 2nd primorial is 6, and both 2*36-1 & 2*36+1 are primes, with corresponding k=2.

Prog

(PARI) isok(n) = {my(q = nextprime(prime(n)+1)); for (k=1, q, x = k*prod(i=1, n, prime(i))^2; if (isprime(x-1) && isprime(x+1), return (1)); ); 0; } \\ Michel Marcus, Nov 14 2018

Crossrefs

Cf. A099160 (corresponding primes), A099162 (k values).

Sequence in context: A205962 A134220 A179146 * A369592 A033077 A190912

Adjacent sequences: A099158 A099159 A099160 * A099162 A099163 A099164

Keyword

nonn,more

Author

Pierre CAMI, Oct 01 2004

Status

approved