1,1

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

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.

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

Cf. A014574.

Sequence in context: A209199 A215328 A107298 * A257905 A305878 A093924

Adjacent sequences: A195101 A195102 A195103 * A195105 A195106 A195107

nonn

Juri-Stepan Gerasimov, Dec 16 2011

approved