A085004 - OEIS

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A085004

a(n)=2*A085003(n)-n.

1, 2, 1, 0, -1, 0, 1, 0, -1, -2, -1, 0, 1, 0, -1, 0, 1, 2, 1, 0, 1, 2, 3, 2, 1, 0, 1, 2, 1, 0, -1, 0, 1, 2, 1, 0, 1, 2, 3, 2, 1, 2, 3, 4, 3, 2, 1, 2, 3, 2, 1, 0, 1, 2, 1, 0, -1, 0, 1, 2, 1, 0, 1, 2, 3, 2, 1, 0, 1, 2, 1, 0, -1, 0, 1, 0, -1, -2, -1, 0, 1, 0, -1, 0, 1, 2, 1, 0, -1, 0, 1, 0, -1, -2, -1, 0, -1, -2, -3, -2, -1, 0, -1, -2, -1, 0, 1, 0, -1, 0, 1, 2, 1, 0, -1

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..115.

FORMULA

|a(n+1)-a(n)| = 1. - Charles R Greathouse IV, Feb 07 2013

PROG

(PARI) 2*sum(k=1, n, (k+sqrtint(5*k^2))%4>1)-n \\ Charles R Greathouse IV, Feb 07 2013

CROSSREFS

Cf. A083035, A083036, A083037, A083038, A085003, A085005.

Sequence in context: A215030 A175816 A227573 * A095774 A266874 A308343

Adjacent sequences: A085001 A085002 A085003 * A085005 A085006 A085007

KEYWORD

sign

AUTHOR

Benoit Cloitre, Jun 17 2003

STATUS

approved