The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A102996 Numbers n such that 4*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
 2, 4, 26, 1271, 1412, 3328, 4676, 47051, 67664 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Also numbers n such that (43*10^n+11)/9 is prime. a(10) > 10^5. - Robert Price, Jun 01 2015 LINKS Makoto Kamada, Prime numbers of the form 477...779. FORMULA a(n) = A101733(n) + 1. MATHEMATICA Do[ If[ PrimeQ[(43*10^n + 11)/9], Print[n]], {n, 0, 10000}] CROSSREFS Cf. A002275, A101733. Sequence in context: A218077 A240040 A088888 * A189896 A095182 A104465 Adjacent sequences:  A102993 A102994 A102995 * A102997 A102998 A102999 KEYWORD more,nonn AUTHOR Robert G. Wilson v, Jan 17 2005 EXTENSIONS a(8) from Erik Branger, May 01 2013, submitted by Ray Chandler, Aug 16 2013 a(9) from Robert Price, Jun 01 2015 STATUS approved

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

Last modified May 19 18:35 EDT 2022. Contains 353847 sequences. (Running on oeis4.)