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A355601 a(1) = 47. For n > 1, a(n) = smallest prime q such that q^(a(n-1)-1) == 1 (mod a(n-1)^2). 5
47, 53, 521, 6037, 3347, 4931, 105667, 1131259, 4739509, 175166071, 3834885547 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Is this overall an increasing sequence or does it enter a cycle?
The sequence decreases for the first time at n = 5.
LINKS
MATHEMATICA
nxt[a_]:=Module[{q=3}, While[PowerMod[q, a-1, a^2]!=1, q=NextPrime[q]]; q]; NestList[ nxt, 47, 10] (* The program will take a long time to run. *) (* Harvey P. Dale, Jan 31 2023 *)
PROG
(PARI) seq(start, terms) = my(x=start, i=1); print1(start, ", "); while(1, forprime(q=1, , if(Mod(q, x^2)^(x-1)==1, print1(q, ", "); x=q; i++; if(i >= terms, break({2}), break))))
seq(47, 20) \\ Print initial 20 terms of sequence
CROSSREFS
Row n = 15 of A249162.
Sequence in context: A155139 A106279 A275022 * A048581 A169716 A045140
KEYWORD
nonn,hard,more
AUTHOR
Felix Fröhlich, Jul 09 2022
STATUS
approved

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Last modified July 25 03:25 EDT 2024. Contains 374586 sequences. (Running on oeis4.)