A178629 Numbers k such that A003418(k-1) = lcm(1,2,...,k-1) is congruent to 1 modulo k.

2, 11, 29, 787, 15773

Offset

1,1

Comments

Numbers k such that A158851(k-1) = 1.

k must be prime.

No further terms below 3.8*10^8. - Max Alekseyev, Jun 19 2011

Links

Table of n, a(n) for n=1..5.

Example

For the first nontrivial example: lcm(1,2,3,4,5,6,7,8,9,10) = 2520 and 2520 mod 11 = 1, so 11 is in the sequence.

Mathematica

fQ[n_] := Mod[ LCM @@ Range[n - 1], n] == 1; k = 2; lst = {}; While[k < 10^6, If[ fQ@k, Print@k; AppendTo[lst, k]]; k++ ]; lst (* Robert G. Wilson v, Jun 02 2010 *)
Select[Range[2, 16000], Mod[LCM@@(Range[#-1]), #]==1&] (* Harvey P. Dale, Oct 01 2024 *)

Prog

(PARI) { L=1; for(n=2, 10^8, if(ispseudoprimepower(n, &p), if(p==n&&L%n==1, print(n)); L*=p); ); } \\ Max Alekseyev, Oct 04 2024

Crossrefs

Cf. A158851.

Sequence in context: A285812 A140745 A356567 * A062802 A103830 A162260

Adjacent sequences: A178626 A178627 A178628 * A178630 A178631 A178632

Keyword

nonn,more

Author

Nick Hobson, May 31 2010

Extensions

Offset changed to 1 by Jinyuan Wang, May 02 2020

Status

approved