1237951

Appears in sequences

• a(n) = m*(m+1)/2, where m = floor(n^(5/2)).at n=18A185542
• Fermat pseudoprimes n to base 3 for which sqrt(8*n + 1) is an integer.at n=39A217841
• Pseudoprimes to base 3 that are not squarefree.at n=18A244065
• Triangular numbers k such that phi(k) is also a triangular number, where phi(k) is the Euler totient function (A000010).at n=7A287472
• Pseudoprimes to base 3 that are not squarefree, including the non-coprime pseudoprimes.at n=20A306452