A097014 Smallest x such that sigma(x) mod 210 = n.
104, 1, 211, 2, 3, 8311689, 5, 4, 7, 3698, 399, 130321, 6, 9, 13, 8, 1477, 2458624, 10, 725904, 19, 676, 6751, 18766224, 14, 52707600, 489, 24649, 12, 220433409, 29, 16, 21, 1250, 2779, 3694084, 22, 5184, 37, 18, 27, 1382976, 20, 729, 43, 128, 217
Offset: 0
Examples
Several numbers belonging to odd residues are either large squares or twice-squares. E.g.: r = n = 209: a(209) = 36324729 = 6027^2, sigma(6027^2) = 210*172974 + 209. Full set is easily available running through squares or twice squares.
Links
- Michel Marcus, Table of n, a(n) for n = 0..209
Comments