A059787 Distance between 2*(n-th prime) and next prime.

1, 1, 1, 3, 1, 3, 3, 3, 1, 1, 5, 5, 1, 3, 3, 1, 9, 5, 3, 7, 3, 5, 1, 1, 3, 9, 5, 9, 5, 1, 3, 1, 3, 3, 9, 5, 3, 5, 3, 1, 1, 5, 1, 3, 3, 3, 9, 3, 3, 3, 1, 1, 5, 1, 7, 15, 3, 5, 3, 1, 3, 1, 3, 9, 5, 7, 11, 3, 7, 3, 3, 1, 5, 5, 3, 3, 9, 3, 7, 3, 1, 11, 1, 11, 3, 1, 9, 5, 7, 3, 3, 9, 3, 1, 11, 3, 1, 7, 3, 5, 3, 3

Offset

1,4

Comments

If a(n)=1 then prime(n) is a Sophie Germain prime.

Links

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

Maple

with(numtheory): [seq(nextprime(2*ithprime(k))-2*ithprime(k), k=1..256)];

Mathematica

Table[n2=2Prime[n]; NextPrime[n2]-n2, {n, 110}] (* Harvey P. Dale, Jun 07 2012 *)

Prog

(PARI) a(n) = my(pp=2*prime(n)); nextprime(pp) - pp; \\ Michel Marcus, Mar 22 2020

Crossrefs

Cf. A005385, A005384.

Sequence in context: A119979 A143149 A268498 * A081325 A132680 A105595

Adjacent sequences: A059784 A059785 A059786 * A059788 A059789 A059790

Keyword

nonn

Author

Labos Elemer, Feb 22 2001

Status

approved