1312350

Appears in sequences

• Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of m; set a(n) = -1 if some fraction i/n never appears.at n=43A066849
• Numbers k such that k + 1, 2k + 1, 3k + 1, 4k + 1, and 6k + 1 are all prime.at n=21A333721