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

Author

Juri-Stepan Gerasimov, Dec 16 2011

Keywords

• nonn

Comments

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

Examples

			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.
		

Links

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

Crossrefs

Cf. A014574, A158866.

Programs

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

Extensions

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