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A073445 Second differences of A002808, the sequence of composites. 3
0, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, -1, 0, 0, 0, 1, 0, -1, 0, 0, 0, 1, -1, 0, 1, 0, -1, 0, 1, -1, 0, 0, 0, 1, -1, 0, 0, 0, 1, 0, -1, 0, 0, 0, 1, -1, 0, 1, 0, -1, 0, 0, 0, 1, -1, 0, 1, -1, 0, 0, 0, 1, -1, 0, 0, 0, 0, 0, 1, -1, 0, 1, 0, -1, 0, 1, 0, -1, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, 0, 1, -1, 0, 0, 0, 1, 0, -1, 0, 0, 0, 0, 0, 0, 0, 1, 0, -1, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n)=c[n+2]-2c[n+1])+c[n], where c(n)=A002808(n).

a(n) = A073783(n+1) - A073783(n). - Reinhard Zumkeller, Jan 10 2013

MATHEMATICA

c[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] Table[(c[w+2]-2*c[w+1])+c[w]), {w, 1, 1000}]

PROG

(Haskell)

a073445 n = a073445_list !! (n-1)

a073445_list = zipWith (-) (tail a073783_list) a073783_list

-- Reinhard Zumkeller, Jan 10 2013

CROSSREFS

Also first differences of A054546.

Cf. A002808, A054546.

Sequence in context: A188510 A131734 A134452 * A179081 A113217 A147781

Adjacent sequences:  A073442 A073443 A073444 * A073446 A073447 A073448

KEYWORD

sign

AUTHOR

Labos Elemer, Aug 01 2002

STATUS

approved

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Last modified February 21 22:56 EST 2018. Contains 299427 sequences. (Running on oeis4.)