123192

Appears in sequences

• Numbers k such that phi(prime(k)-1) == 0 (mod k).at n=14A067733
• 1/n * sum over d|n of {mu(n/d) * (4d)! / d!^4}.at n=2A074652
• a(n) = 81*n^2 - 9.at n=38A157909
• a(n) is the number of configurations of n indistinguishable pairs placed on the vertices of the ladder graph P_2 X P_n such that all but two such pairs are joined by an edge.at n=13A318267