A046789 Lower prime of the second gap of 2n between primes.

5, 13, 31, 359, 181, 211, 293, 1933, 1069, 1637, 1951, 2179, 3137, 3271, 4831, 10799, 8467, 12853, 38393, 20809, 34981, 36389, 91033, 73189, 45893, 25471, 40289, 153191, 58831, 102701, 190409, 107377, 221327, 290249, 175141, 360091

Offset: 1

Author

Jud McCranie

Keywords

• nonn

Examples

			The second prime gap of 4 is at 13 to 17, so a(2)=13.
		

References

• Enoch Haga, Exploring Prime Numbers on Your PC, 2nd edition, 1998, ISBN 1-885794-16-9, Table 4, pages 38-39.

Links

• Robert G. Wilson v, Table of n, a(n) for n = 1..257

Crossrefs

Cf. A000230, A046728.

Programs

Mathematica

Flatten[Table[First /@ Take[Select[Partition[Prime[Range[32000]], 2, 1], Differences[#] == {2 n} &], {2}], {n, 36}]] (* Jayanta Basu, Jun 28 2013 *)
tt[] := -2; p0 = NextPrime@2; p1 = NextPrime@p0; While[p0 < 25000000, diff = (p1 - p0)/2; If[tt[diff] == -1, tt[diff] = p0]; If[tt[diff] == -2, tt[diff] = -1]; {p0, p1} = {p1, NextPrime@p1}]; tt@# & /@ Range@77 (* _Robert G. Wilson v, Nov 26 2020 *)

Formula

a(n) = A000230(n) + A046728(n). - Robert G. Wilson v, Nov 26 2020