81217

Appears in sequences

• Strong pseudoprimes to base 38.at n=31A020264
• Strong pseudoprimes to base 65.at n=33A020291
• Numbers n such that phi(n)=d_1!!*d_2!!*...*d_k!! where d_1 d_2 ... d_k is the decimal expansion of n.at n=34A139408
• Sum of all repeated parts of all partitions of n.at n=27A163986
• Table read by rows: number of connected components of polyhedra in the quarter cubic honeycomb consisting of k tetrahedra and n-k truncated tetrahedra, up to translation, rotation, and reflection of the honeycomb, 0<=k<=n.at n=56A384486