A079721 Interemirp sequence: average of emirp pairs, analogous to interprimes.

15, 24, 34, 54, 72, 76, 88, 102, 110, 131, 153, 162, 173, 189, 255, 324, 342, 353, 374, 545, 705, 721, 736, 741, 747, 756, 765, 838, 922, 939, 947, 960, 969, 977, 987, 1000, 1015, 1026, 1032, 1047, 1065, 1080, 1094, 1100, 1106, 1130, 1152, 1167, 1187

Offset

1,1

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Michael Joseph Halm, Sequences

Formula

a(n) = (A006567(n) + A006567(n+1))/2 where A006567(n) is the n-th emirp.

Example

a(1) = 15 because the first two emirps are 13 and 17 and (13 + 17)/2 = 15

Mathematica

Map[Apply[Total, {##}]/2 &, Partition[Select[Prime[Range[5, 196]], And[PrimeQ@ IntegerReverse[#], ! PalindromeQ[#] ] &], 2, 1]] (* Michael De Vlieger, Aug 26 2025 *)

Crossrefs

Cf. A006567, A024675.

Sequence in context: A269316 A081829 A348730 * A362812 A089952 A373406

Adjacent sequences: A079718 A079719 A079720 * A079722 A079723 A079724

Keyword

nonn,base

Author

Michael Joseph Halm, Feb 17 2003

Extensions

a(4) corrected by Sean A. Irvine, Aug 25 2025

Status

approved