A152598 Records in A001917.

1, 2, 6, 8, 18, 24, 31, 38, 72, 105, 129, 630, 1285, 1542, 2048, 3112, 3512, 7710, 7760, 9728, 27594, 48834, 60787, 104694, 140896, 282224, 384800, 683720, 1205998, 1240672, 1407592, 4012472, 4429250, 4628480, 16657248, 69273666, 107700228, 254290896, 319233186

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..47

Formula

a(n) = A001917(A152597(n)). - Amiram Eldar, Nov 16 2023

Example

First few terms of A001917 are 1, 1, 2, 1, 1, 2, 1, 2, 1, 6, so a(1) to a(3) are 1, 2, 6.

Mathematica

ord[n_]:=Module[{x=1}, While[PowerMod[2, x, n]!=1, x++]; (n-1)/x]; DeleteDuplicates[ ord/@Prime[Range[2, 10^5]], GreaterEqual] (* The program generates the first 21 terms of the sequence. *) (* Harvey P. Dale, Oct 09 2022 *)

Prog

(Magma) R:=[]; r:=0; for n in [2..100000] do p:=NthPrime(n); a:=(p-1)/Modorder(2, p); if r lt a then r:=a; Append(~R, a); end if; end for; print R;

Crossrefs

Cf. A001917 ((p-1)/x, where p = prime(n) and x = smallest positive integer such that 2^x == 1 mod p), A152597 (where records occur in A001917).

Sequence in context: A259026 A178758 A024431 * A154610 A053658 A032393

Adjacent sequences: A152595 A152596 A152597 * A152599 A152600 A152601

Keyword

nonn

Author

Klaus Brockhaus, Dec 09 2008

Extensions

More terms from Vassilis Papadimitriou, Mar 06 2010

More terms from Vassilis Papadimitriou, Mar 19 2010

a(37) from Amiram Eldar, Mar 08 2019

a(38)-a(39) from Amiram Eldar, Nov 16 2023

Status

approved