218751

Appears in sequences

• Number of series-reduced planted trees with n leaves. Also the number of essentially series series-parallel networks with n edges; also the number of essentially parallel series-parallel networks with n edges.at n=13A000669
• Trimorphic but not bimorphic nor automorphic.at n=39A056032
• Smallest number m > 1 such that m^2 == 1 (mod 10^n).at n=5A181539
• Numbers n with k digits such that n^2 == 1 (mod 10^k).at n=26A181607
• Numbers whose squares have 2R-1 digits, such that the number represented by leftmost R digits and number represented by rightmost R digits divide each other evenly.at n=32A216233
• (2*16^(5^n) - 1) mod 10^n: a sequence of trimorphic numbers ending in 1.at n=5A224474
• Numbers n such that the product of proper divisors of n ends with n and n is not a multiplicatively perfect number (A007422).at n=28A278474