The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A125504 Smallest number k such that the numerator of alternating generalized harmonic number H'(k,n) = Sum[ (-1)^(i+1) * 1/i^n, {i,1,k} ] is a prime. 0
 3, 2, 2, 3, 2, 19, 2, 146, 87, 3, 16, 3, 2, 249, 15, 87, 2, 699, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = 2 for n in A000043. a(n) = 3 for n in {1,4,10,12,24,27,39,...}. a(n) = 5 for n in {26,76,132,205,238,...}. a(n) = 9 for n in {100,200,...}. a(n) = 15 for n in {15,33,65,...}. a(21) = 18. a(22) = 13. a(41) = 6. a(72) = 11. a(173) = 8. a(20) > 2100 - Max Alekseyev, Jul 07 2009 LINKS Eric Weisstein's World of Mathematics, Harmonic Number CROSSREFS Cf. A058313, A119682, A120296, A001008, A000043. Sequence in context: A049234 A299351 A294299 * A243929 A075392 A069901 Adjacent sequences:  A125501 A125502 A125503 * A125505 A125506 A125507 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Dec 28 2006, Jan 31 2007 EXTENSIONS More terms from Max Alekseyev, Jul 07 2009 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 8 08:54 EDT 2020. Contains 333313 sequences. (Running on oeis4.)