A061009 a(n) = -2 + Sum_{j=1..n} (-(n-1)!) mod n.

-2, -1, 0, 2, 3, 3, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 17, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 20, 20, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 24, 24, 24, 24, 24

Offset: 1

Author

Henry Bottomley, Apr 12 2001

Keywords

• sign

Examples

			a(6)=3 since -2 + (-1 mod 1) + (-1 mod 2) + (-2 mod 3) + (-6 mod 4) + (-24 mod 5) + (-120 mod 6) = -2 + 0 + 1 + 1 + 2 + 1 + 0 = 3.
		

Crossrefs

Cf. A000040, A000142, A061006, A061007, A061008.

Formula

a(n) = a(n-1) + A061007(n) = A061008(n) - 2. For n > 3, a(n) = pi(n) = A000720(n) where pi(n) is the number of primes less than or equal to n.