This site is supported by donations to The OEIS Foundation.

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A231989 Least prime p such that p(0),...,p(n) are all primes, where p(0) = p, then p(i+1) = triangular(p(i))+1. 1
 3, 3, 43, 236367611, 31542795419 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Triangular(p) = p*(p+1)/2. LINKS EXAMPLE a(2) = 3 because 3 is the least prime such that the following are two primes: p1 = 3 * 4 / 2 + 1 = 7. p2 = 7 * 8 / 2 + 1 = 29. a(3) = 43 because 43 is the least prime such that the following 3 numbers are prime: p1 = 43 * 44 / 2 + 1 = 947. p2 = 947 * 948 / 2 + 1 = 448879. p3 = 448879 * 448880 / 2 + 1 = 100746402761. CROSSREFS Cf. A000040, A000217, A231847, A231988. Sequence in context: A082394 A086889 A269909 * A059495 A174325 A290366 Adjacent sequences:  A231986 A231987 A231988 * A231990 A231991 A231992 KEYWORD nonn,hard,more AUTHOR Alex Ratushnyak, Nov 16 2013 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 January 17 05:26 EST 2019. Contains 319207 sequences. (Running on oeis4.)