A022820 - OEIS

A022820

[ n/1 ] - [ (n-1)/2 ] + [ (n-2)/3 ] - ... + ((-1)^n)[ 2/(n-1) ].

2, 2, 3, 4, 5, 4, 6, 7, 8, 7, 8, 9, 12, 10, 11, 12, 13, 12, 15, 16, 17, 14, 16, 17, 20, 19, 20, 21, 22, 19, 22, 23, 26, 24, 25, 26, 29, 26, 27, 28, 29, 28, 33, 34, 35, 30, 32, 33, 36, 35, 36, 37, 40, 37, 40, 41, 42, 39, 40, 41, 46, 42, 45, 46, 47, 46, 49, 50, 51, 46

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,1

LINKS

Table of n, a(n) for n=2..71.

PROG

(PARI) a(n) = sum(i=1, n-1, (-1)^(i+1)*floor((n-i+1)/i)) \\ for n>1 Michel Marcus, Mar 22 2013

CROSSREFS

Sequence in context: A252462 A094457 A275495 * A292259 A241397 A331049

Adjacent sequences: A022817 A022818 A022819 * A022821 A022822 A022823

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved