A063793 a(n) = Min{ q prime | nextprime(q) - q - 1 = prime(n)}, or 0 if none exist.

7, 23, 89, 199, 113, 523, 887, 1669, 4297, 5591, 30593, 16141, 15683, 28229, 35617, 43331, 34061, 134513, 31397, 404597, 542603, 461717, 404851, 604073, 1444309, 1388483, 2238823, 1468277, 492113, 3851459, 1357201, 3826019, 7621259, 13626257, 8421251, 49269581

Offset

2,1

Comments

Conjecture: a(n) > 0 for n > 1.

Links

Charles R Greathouse IV, Table of n, a(n) for n = 2..217

Formula

a(n) = A000230((prime(n)+1)/2). - Charles R Greathouse IV, Apr 30 2015

Example

The 3rd odd prime is 7 = 97 - 89 - 1 and for all p < 89 nextprime(p) - p <> 8; therefore a(3) = 89.

Prog

(PARI) a(n)=my(t=prime(n)+1, p=2); forprime(q=3, , if(q-p==t, return(p)); p=q) \\ Charles R Greathouse IV, Apr 30 2015

Crossrefs

Cf. A046933.

Sequence in context: A322269 A303890 A003540 * A217233 A316734 A096327

Adjacent sequences: A063790 A063791 A063792 * A063794 A063795 A063796

Keyword

nonn

Author

Reinhard Zumkeller, Aug 18 2001

Extensions

Offset changed by Charles R Greathouse IV, Apr 30 2015

a(26)-a(37) from Charles R Greathouse IV, Apr 30 2015

Status

approved