A261929 a(n) is the number of different pairs (p,q) mod n not of the form (x*y,x+y) mod n for any (x,y).

0, 1, 3, 8, 10, 18, 21, 36, 45, 55, 55, 96, 78, 112, 135, 160, 136, 216, 171, 280, 273, 286, 253, 408, 350, 403, 432, 560, 406, 630, 465, 656, 693, 697, 805, 1008, 666, 874, 975, 1180, 820, 1260, 903, 1408, 1485, 1288, 1081, 1728, 1323, 1675, 1683, 1976, 1378, 2025, 2035, 2352, 2109, 2059, 1711, 2880, 1830, 2356

Offset: 1

Author

Thomas Kerscher, Sep 06 2015

Keywords

• nonn

Examples

			a(2) = 1 because only the pair (1,1) mod 2 doesn't exist as result from any (x*y,x+y) mod 2.
		

Crossrefs

Cf. A261928 (number of pairs that have such a form).

Formula

a(n) = n^2 - A261928(n).