This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A109621 Numbers n such that the numerator of sum_{k=0..n} 1/k!, in reduced form, is prime. 0
 1, 2, 5, 9, 24, 32, 321, 343, 352, 511, 685, 807, 966, 1079, 1274, 1381, 2016, 3226 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Terms through 807 correspond to certified primes. LINKS EXAMPLE sum_{k=0..9} 1/k! = 98641/36288 and 98641 is prime, so 9 is in the sequence. MATHEMATICA s = 0; Do[s += 1/n!; k = Numerator[s]; If[PrimeQ[k], Print[n]], {n, 0, 3300}] CROSSREFS Sequence in context: A088356 A192477 A047044 * A075200 A075198 A006405 Adjacent sequences:  A109618 A109619 A109620 * A109622 A109623 A109624 KEYWORD hard,more,nonn AUTHOR Ryan Propper (rpropper(AT)stanford.edu), Aug 01 2005 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .