128627

Appears in sequences

• Strong pseudoprimes to base 6.at n=33A020232
• Strong pseudoprimes to base 21.at n=29A020247
• Strong pseudoprimes to base 55.at n=30A020281
• Strong pseudoprimes to base 56.at n=21A020282
• Strong pseudoprimes to base 73.at n=30A020299
• Pentagonal numbers (A000326) that are also brilliant numbers (A078972).at n=17A113941
• Binomial transform of [1, 4, 6, 4, 1, 1, -1, 1, -1, 1, ...].at n=35A140227
• Semiprimes of the form n*(3*n-1)/2.at n=31A245365
• Semiprimes of the form (4*n + 1)*(6*n + 1) = 24*n^2 + 10*n + 1.at n=12A255584
• a(n) is the smallest k such that the p-rank of (Z/kZ)* is 2, where p = prime(n) and (Z/kZ)* is the multiplicative group of integers modulo n.at n=20A307434