This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A181471 a(n) = number of numbers of the form k^2-1 having n-th prime as largest prime divisor. 4
 1, 4, 8, 16, 20, 34, 47, 72, 95, 126, 168, 208, 262, 343, 433, 507, 634, 799, 976, 1146, 1439, 1698, 2082, 2370, 2679 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Theorem (Artur Jasinski): zero does not occur in this sequence. Proof: (p-1)^2-1=(p-2)p. This means that p is greatest prime divisor of (p-1)^2-1 for every p. a(2)-a(25)=total number of terms in A181447-A181470. LINKS CROSSREFS Cf. A175607, A175901-A175904, A181447-A181470. Sequence in context: A312805 A312806 A036693 * A272753 A272804 A237990 Adjacent sequences:  A181468 A181469 A181470 * A181472 A181473 A181474 KEYWORD more,nonn AUTHOR Artur Jasinski, Oct 21 2010, Oct 22 2010. 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 July 17 08:40 EDT 2019. Contains 325097 sequences. (Running on oeis4.)