A195104 Smallest prime p such that p*t(n) +- 1 is a twin prime pair, where t(n)=A014574(n) is the n-th twin prime average.

3, 2, 5, 11, 2, 11, 3, 29, 101, 199, 29, 7, 13, 11, 29, 71, 13, 3, 71, 101, 29, 43, 79, 5, 11, 11, 5, 29, 61, 2, 2, 11, 19, 11, 29, 5, 11, 7, 41, 19, 181, 19, 59, 5, 11, 7, 29, 11, 41, 179, 41, 13, 61, 181, 19, 241, 139, 331, 271, 3, 59, 5, 41, 89, 19, 2, 5, 131, 59, 5, 5, 509, 2

Offset

1,1

Comments

a(n) = 2 for n in A158866. - Robert Israel, Mar 07 2021

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

a(4)=11 because 11*A014574(4) +- 1 = 11*18 +- 1 = 198 +- 1 is a twin prime pair, A014574(4) +- 1 = 18 +- 1 is also a twin prime pair, and 11 is prime.

Maple

A195104 := proc(n)
    k := A014574(n) ;
    for i from 1 do
        p := ithprime(i) ;
        if isprime(p*k-1) and isprime(p*k+1) then
            return p;
        end if;
    end do:
end proc:
seq(A195104(n), n=1..60) ; # R. J. Mathar, Dec 16 2011

Crossrefs

Cf. A014574, A158866.

Sequence in context: A209199 A215328 A107298 * A338879 A257905 A379657

Adjacent sequences: A195101 A195102 A195103 * A195105 A195106 A195107

Keyword

nonn

Author

Juri-Stepan Gerasimov, Dec 16 2011

Extensions

a(64) corrected by Robert Israel, Mar 07 2021

Status

approved