A072614 a(n) = Sum_{k = 1..n} (-1)^(n reduced mod k).

1, 2, 1, 2, 1, 4, -1, 4, 1, 4, -1, 6, -3, 8, -1, 4, -1, 8, -5, 10, -3, 8, -5, 10, -5, 10, -3, 8, -5, 14, -11, 14, -7, 12, -5, 12, -9, 14, -7, 12, -9, 18, -15, 20, -9, 14, -11, 16, -11, 18, -11, 16, -13, 22, -15, 20, -13, 18, -15, 24, -21, 26, -15, 18, -11, 20, -17, 22, -15, 24, -21, 28, -25, 30, -19, 24, -17, 26, -23, 28, -19, 24

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

Lim_{n -> infinity} abs(a(n))/n = C = 0.30684(3)....

Mathematica

Table[ Sum[(-1)^ Mod[n, k], {k, 1, n}], {n, 1, 81} ]

Prog

(PARI) a(n)=sum(k=1, n, (-1)^(n%k))

Crossrefs

Sequence in context: A164799 A274451 A193787 * A287597 A238552 A257523

Adjacent sequences: A072611 A072612 A072613 * A072615 A072616 A072617

Keyword

sign

Author

Benoit Cloitre, Aug 10 2002

Status

approved