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A061009 a(n) = -2 + Sum_{j=1..n} (-(n-1)!) mod n. 3
-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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..93.

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.

EXAMPLE

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.

MAPLE

P:=proc(n) local a, i, w; a:=-2; print(a); for i from 1 by 1 to n do w:=((i-1)! mod (i+1)); a:=a+w; print(a); od; end: P(1000); # Paolo P. Lava, Apr 23 2007

CROSSREFS

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

Sequence in context: A104770 A296529 A110280 * A144106 A104558 A206022

Adjacent sequences: A061006 A061007 A061008 * A061010 A061011 A061012

KEYWORD

sign

AUTHOR

Henry Bottomley, Apr 12 2001

STATUS

approved

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Last modified November 27 09:57 EST 2022. Contains 358367 sequences. (Running on oeis4.)