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A061009
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-2+sum_j (-(n-1)! mod n) over 0<j<=n.
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3
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-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; internal format)
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OFFSET
| 1,1
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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.
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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.
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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 (paoloplava(AT)gmail.com), Apr 23 2007
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CROSSREFS
| Cf. A000040, A000142, A061006, A061007, A061008.
Sequence in context: A167749 A104770 A110280 * A144106 A104558 A206022
Adjacent sequences: A061006 A061007 A061008 * A061010 A061011 A061012
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KEYWORD
| sign
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Apr 12 2001
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