27045

Appears in sequences

• a(n)! begins with 2^n.at n=13A059449
• Number of n X n binary arrays symmetric under horizontal reflection with all ones connected only in a 1100-0100-0111-0001 pattern in any orientation.at n=13A147194
• Solutions y of the Mordell equation y^2 = x^3 - 3a^2 - 1 for a = 0,1,2, ... (solutions x are given by A053755).at n=15A173200
• Where the first run of length n occurs in maximally unpredictable sequences A007061, A038219.at n=14A201882
• Ulam numbers k such that k/3 is also an Ulam number.at n=39A287212