A352162 a(n) is the first start of a sequence of exactly n lower twin primes under the iteration p -> 3*p+2.

11, 3, 32969, 211725989

Offset

1,1

Comments

a(n), 3*a(n)+2, 9*(a(n)+1)-1, ..., 3^(n-1)*(a(n)+1)-1 are lower twin primes but 3^n*(a(n)+1)-1 is not.

Links

Table of n, a(n) for n=1..4.

Example

a(3) = 32969 because 32969 and 32971 are primes, 3*32969+2 = 98909 and 98911 are primes, 3*98909+2 = 296729 and 296731 are primes, but 3*296729+2 = 890189 and 890191 are not both primes.

Crossrefs

Cf. A001359.

Sequence in context: A079841 A110782 A088073 * A010187 A372761 A248175

Adjacent sequences: A352159 A352160 A352161 * A352163 A352164 A352165

Keyword

nonn,more

Author

Robert Israel, Mar 06 2022

Status

approved