This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A285087 Numbers n such that the number of partitions of n^2-1 is prime. 3
 2, 13, 21, 46909 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Because asymptotically A000041(n^2-1) ~ exp(Pi*sqrt(2/3*(n^2-1))) / (4*sqrt(3)*(n^2-1)), the sum of the prime probabilities ~1/log(A000041(n^2-1)) is diverging and there are no obvious restrictions on primality; therefore, this sequence may be conjectured to be infinite. a(5) > 50000. LINKS Chris K. Caldwell, Top twenty prime partition numbers, The Prime Pages. Eric Weisstein's World of Mathematics, Partition Function P Eric Weisstein's World of Mathematics, Integer Sequence Primes FORMULA {n: A000041(n^2-1) in A000040}. EXAMPLE 13 is in the sequence because A000041(13^2-1) = 228204732751 is a prime. PROG (PARI) for(n=1, 2000, if(ispseudoprime(numbpart(n^2-1)), print1(n, ", "))) CROSSREFS Cf. A000041, A046063, A072213, A284594, A285086, A285088. Sequence in context: A182459 A303669 A084651 * A085509 A127485 A061385 Adjacent sequences:  A285084 A285085 A285086 * A285088 A285089 A285090 KEYWORD nonn,hard,more AUTHOR Serge Batalov, Apr 09 2017 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 April 19 06:30 EDT 2019. Contains 322237 sequences. (Running on oeis4.)