This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A185439 Emirp gaps. Differences between consecutive emirps. 1
 4, 14, 6, 34, 2, 6, 18, 10, 6, 36, 8, 10, 12, 20, 112, 26, 10, 12, 30, 312, 8, 24, 6, 4, 8, 10, 8, 138, 30, 4, 12, 14, 4, 12, 8, 18, 12, 10, 2, 28, 8, 22, 6, 6, 6, 42, 2, 28, 12, 8, 12, 4, 6, 6, 2, 6, 12, 10, 20, 4, 18, 20, 60, 18, 10, 20, 10, 14, 18, 16, 12, 12, 12, 36, 24, 14, 4, 18, 38, 12, 54, 10, 8, 12, 36, 22, 20 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Gaps between consecutive primes whose reversal is a different prime. This is to Differences between consecutive primes (A001223) as emirps (A006567) are to primes (A000040). This was indirectly suggested to me in a facebook conversation with Kevin L. Schwartz. One may use this to derive other sequences: records in emirp gaps; lower of pair of consecutive emirps with record gap; larger of pair of emirps with record gaps, by analogy with A005250, A002386, A000101. LINKS FORMULA a(n) = A006567(n+1) - A006567(n). EXAMPLE Here are the first 9 emirps: 13, 17, 31, 37, 71, 73, 79, 97, 107. Hence the first 8 gaps between consecutive emirps are: (17-13) = 4. (31-17) = 14. (37-31) = 6. (71-37) = 34. (73-71) = 2 (i.e. 71 and 73 are a pair of "twin prime emirps") (79-73) = 6. (97-79) = 18. (107-97) = 10. So far, we see a minimum gap of 2, and a maximum of 34. MATHEMATICA emirpQ[n_]:=Module[{idn=IntegerDigits[n], ridn}, ridn=Reverse[idn]; idn!=ridn&&PrimeQ[FromDigits[ridn]]] Take[Differences[Select[Prime[Range[1000]], emirpQ]], 90]  (* Harvey P. Dale, Feb 18 2011 *) CROSSREFS Cf. A000040, A000101, A001223, A002386, A006567. Sequence in context: A131702 A276826 A029661 * A304458 A133856 A018853 Adjacent sequences:  A185436 A185437 A185438 * A185440 A185441 A185442 KEYWORD nonn,base,easy AUTHOR Jonathan Vos Post, Feb 03 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)