login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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. 1
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, 211, 19, 2, 5, 131, 59, 5, 5, 509, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..73.

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.

Sequence in context: A209199 A215328 A107298 * A257905 A305878 A093924

Adjacent sequences:  A195101 A195102 A195103 * A195105 A195106 A195107

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Dec 16 2011

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 25 19:28 EDT 2020. Contains 338012 sequences. (Running on oeis4.)