The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A280015 a(n) is the least k such that A056619(k) = prime(n). 0
 1, 2, 12, 10, 6, 76, 114, 34, 120, 246, 1386, 616, 1126, 3774, 510, 8220, 2634, 25810, 57936, 46836, 12180, 254940, 54574, 80040, 497146, 801780, 402324, 1003744, 6441196, 2858890, 27821214, 14312640, 47848164, 25049814, 8454126, 45433894, 4262890 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS a(n) is the least number that is a primitive root mod prime(n) but not mod any lower prime. Using the Chinese Remainder Theorem, it is easy to show that such k always exists. LINKS Table of n, a(n) for n=1..37. EXAMPLE 10 is a primitive root mod prime(4) = 7, but not mod 2, 3 or 5. This is the least number with that property, so a(4)=10. MAPLE a[1]:= 1: a[2]:= 2: p:= 3: Cands:= {4, seq(seq(6*i+j, j=[0, 4]), i=1..10^7)}: for n from 3 while Cands <> {} do p:= nextprime(p); r:= numtheory:-primroot(p); s:= select(t -> igcd(t, p-1)=1, {\$1..p-1}); q:= map(t -> r &^t mod p, s); R, Cands:= selectremove(t -> member(t mod p, q), Cands): if R = {} then break fi; a[n]:= min(R); od: seq(a[i], i=1..n-1); CROSSREFS Cf. A056619. Sequence in context: A166544 A081468 A216349 * A343645 A245281 A358505 Adjacent sequences: A280012 A280013 A280014 * A280016 A280017 A280018 KEYWORD nonn AUTHOR Robert Israel, Feb 21 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 1 05:26 EST 2024. Contains 370430 sequences. (Running on oeis4.)