A070963 a(1) = 2; for n >= 2, n = Sum_{1<=k

2, 1, 2, 0, 4, -2, 0, 2, 6, -4, 6, -4, -6, 10, 2, -2, 12, -10, -2, 8, 2, -4, 8, 4, -16, 8, 10, -8, 10, -8, -8, 14, 14, -26, 26, -14, -36, 42, 20, -22, 68, -66, -60, 14, -10, 60, 40, -74, -38, -66, 10, 134, 44, -98, -64, -54, 22, 156, 20, -18, -34, -240, 10, 256, 32, -18, -6, -144, -72, 226, 70, -68, -50, -184, 58, 236, 82

Offset: 1

Author

Leroy Quet, May 16 2002

Keywords

• sign

Examples

			12 = a(1) + a(5) + a(7) + a(11) = 2 + 4 + 0 + 6 because 1, 5, 7 and 11 are the positive integers < 12 and relatively prime to 12.
		

Links

• Sean A. Irvine, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A045545.