This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
(See the program at A204932.)
1 divides 2!-1!, so a(1)=2 2 divides 3!-2!, so a(2)=3 3 divides 4!-3!, so a(3)=4 13 divides 9!-4!, so a(13)=9
f:= proc(n) local t, k, V;
t:= 1:
for k from 1 do
t:= t*k mod n;
if assigned(V[t]) then return k else V[t]:= k fi
od
end proc:
map(f, [$1..100]); # Robert Israel, Nov 11 2024
s[n_] := s[n] = n!; z1 = 80; z2 = 60;
Table[s[n], {n, 1, 30}] (* A000142 *)
u[m_] := u[m] = Flatten[Table[s[k] - s[j], {k, 2, z1}, {j, 1, k - 1}]][[m]]
Table[u[m], {m, 1, z1}] (* A204930 *)
v[n_, h_] := v[n, h] = If[IntegerQ[u[h]/n], h, 0]
w[n_] := w[n] = Table[v[n, h], {h, 1, z1}]
d[n_] := d[n] = First[Delete[w[n], Position[w[n], 0]]]
Table[d[n], {n, 1, z2}] (* A204931 *)
k[n_] := k[n] = Floor[(3 + Sqrt[8 d[n] - 1])/2]
m[n_] := m[n] = Floor[(-1 + Sqrt[8 n - 7])/2]
j[n_] := j[n] = d[n] - m[d[n]] (m[d[n]] + 1)/2
Table[k[n], {n, 1, z2}] (* A204932 *)
Table[j[n], {n, 1, z2}] (* A204933 *)
Table[s[k[n]], {n, 1, z2}] (* A204934 *)
Table[s[j[n]], {n, 1, z2}] (* A204935 *)
Table[s[k[n]] - s[j[n]], {n, 1, z2}] (* A204936 *)
Table[(s[k[n]] - s[j[n]])/n, {n, 1, z2}] (* A204937 *)
(See the program at A204932.)
(See the example at A204932.)
(See the program at A204932.)
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