OFFSET

1,4

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..5000

FORMULA

a(n) = [n(n+1)r] - Sum_{k=1..n} [k*r], where [ ]=floor and r=sqrt(2).

MATHEMATICA

PROG

(PARI) a(n) = floor(sum(k=1, n, frac(k*sqrt(2)))); \\ Michel Marcus, Nov 06 2017

CROSSREFS

KEYWORD

nonn

AUTHOR

Clark Kimberling, Aug 18 2011

STATUS

approved