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%I #10 Apr 04 2020 05:13:39
%S 3757261,10440301,24906181,35391061,35781661,38921941,40890541,
%T 51661261,67342981,75938701,76528741,79017061,91043101,124464181,
%U 149911141,151954501,152670541,152698681,162179581,177779461,184238581,190380061,199495741,228968581,230833441
%N Odd numbers k such that the multiplicative orders of 2 modulo k, k+2 and k+4 are equal.
%H Amiram Eldar, <a href="/A333744/b333744.txt">Table of n, a(n) for n = 1..400</a>
%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativeOrder.html">Multiplicative Order</a>.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Multiplicative_order">Multiplicative order</a>.
%e 3757261 is a term since the multiplicative orders of 2 modulo 3757261, 3757263 and 3757265 are all equal to 250484.
%t f[n_] := MultiplicativeOrder[2, n]; f1 = f[1]; f2 = f[3]; seq = {}; Do[f3 = f[n]; If[f1 == f2 && f2 == f3, AppendTo[seq, n - 4]]; f1 = f2; f2 = f3, {n, 5, 10^8, 2}]; seq
%Y Cf. A002326, A333743.
%K nonn
%O 1,1
%A _Amiram Eldar_, Apr 03 2020