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A088226 a(1)=0, a(2)=0, a(3)=1; for n>3, a(n)=abs(a(n-1)-a(n-2)-a(n-3)). 6
0, 0, 1, 1, 0, 2, 1, 1, 2, 0, 3, 1, 2, 2, 1, 3, 0, 4, 1, 3, 2, 2, 3, 1, 4, 0, 5, 1, 4, 2, 3, 3, 2, 4, 1, 5, 0, 6, 1, 5, 2, 4, 3, 3, 4, 2, 5, 1, 6, 0, 7, 1, 6, 2, 5, 3, 4, 4, 3, 5, 2, 6, 1, 7, 0, 8, 1, 7, 2, 6, 3, 5, 4, 4, 5, 3, 6, 2, 7, 1, 8, 0, 9, 1, 8, 2, 7, 3, 6, 4, 5, 5, 4, 6, 3, 7, 2, 8, 1, 9, 0, 10, 1, 9, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

Conjecture: a(n) = m/2 where m is the smallest even distance from n to a square. - Ralf Stephan, Sep 23 2013

LINKS

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

FORMULA

a(k^2+2m+2)=k-m and a(k^2+2m+1)= m, for k>=0 and 0<=m<=k.

MATHEMATICA

RecurrenceTable[{a[1]==a[2]==0, a[3]==1, a[n]==Abs[a[n-1]-a[n-2]-a[n-3]]}, a, {n, 110}] (* From Harvey P. Dale, Apr 13 2012 *)

PROG

(PARI) a(n)=t=sqrtint(n); if((n-t*t)%2==0, (n-t*t)/2, ((t+1)^2-n)/2) // - Ralf Stephan, Sep 23 2013

(Haskell)

a088226 n = a088226_list !! (n-1)

a088226_list = 0 : 0 : 1 : zipWith3 (\u v w -> abs (w - v - u))

               a088226_list (tail a088226_list) (drop 2 a088226_list)

-- Reinhard Zumkeller, Oct 11 2014

CROSSREFS

Cf. A080096.

Cf. A077623, A077653, A079623, A079624, A080096.

Sequence in context: A155997 A326171 A123223 * A244658 A117586 A307988

Adjacent sequences:  A088223 A088224 A088225 * A088227 A088228 A088229

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Nov 04 2003

STATUS

approved

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Last modified January 18 19:46 EST 2020. Contains 331030 sequences. (Running on oeis4.)