A028669 - OEIS

%I #16 Jul 12 2025 08:32:18

%S 1,42,98784,11587955904,66774437101209600,18861003469034659931443200,

%T 261058346935768909875766027257446400,

%U 177055579258883302762565632026325003745732198400,5884074751780775313126615757455645503567996488345394872320000

%N Galois numbers for p=7; order of group AGL(n,7).

%H Vincenzo Librandi, <a href="/A028669/b028669.txt">Table of n, a(n) for n = 0..34</a>

%H <a href="/index/Gre#groups">Index entries for sequences related to groups</a>.

%F a(n) = 7^n * Product_{k=0..n-1} (7^n - 7^k).

%F a(n) ~ c * 7^(n^2+n), where c = A132035. - _Amiram Eldar_, Jul 12 2025

%t FoldList[ #1*7^#2 (7^#2-1)&, 1, Range[ 20 ] ]

%t a[n_] := 7^n * Product[7^n - 7^k, {k, 0, n-1}]; Array[a, 10, 0] (* _Amiram Eldar_, Jul 12 2025 *)

%o (PARI) a(n) = 7^n * prod(k = 0, n-1, 7^n - 7^k); \\ _Amiram Eldar_, Jul 12 2025

%Y Cf. A028365, A028665, A028667, A028673, A028675, A028679, A028681, A028685.

%Y Cf. A132035.

%K nonn

%O 0,2

%A _Olivier Gérard_