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A080096 a(1)=a(2)=1; a(3)=2; a(n)=abs(a(n-1)-a(n-2)-a(n-3)). 4
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, 8, 3, 7, 4, 6, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..105.

FORMULA

For n>=3 Max( a(k) : 1<=k<=n ) = floor ( sqrt(n+4)).

Special cases: a(n^2+4*n-1)=0; a(n^2-4)=n

Also a( A028557(n))= a(A028557(n+1)); sum(k=(n-1)^2, n^2, a(k)) = n^2

PROG

(PARI) a(n)=local(k, m); if(n<1, 0, k=sqrtint(n+4); m=n+4-k^2; if(m%2, m\2+1, k-m\2))

CROSSREFS

Cf. A028347.

Sequence in context: A051709 A218585 A054656 * A068915 A133925 A071492

Adjacent sequences:  A080093 A080094 A080095 * A080097 A080098 A080099

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 28 2003

STATUS

approved

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Last modified April 24 09:51 EDT 2014. Contains 240963 sequences.