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A046789
Lower prime of the second gap of 2n between primes.
4
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
1,1
REFERENCES
Enoch Haga, Exploring Prime Numbers on Your PC, 2nd edition, 1998, ISBN 1-885794-16-9, Table 4, pages 38-39.
LINKS
FORMULA
a(n) = A000230(n) + A046728(n). - Robert G. Wilson v, Nov 26 2020
EXAMPLE
The second prime gap of 4 is at 13 to 17, so a(2)=13.
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 *)
CROSSREFS
Sequence in context: A146057 A062403 A066688 * A271902 A272539 A066184
KEYWORD
nonn
AUTHOR
STATUS
approved