OFFSET

1,2

COMMENTS

a(n) = floor(2*sqrt(n)) + floor(sqrt(n-1)) - 1 if n belongs to A135106 otherwise a(n) = floor(2*sqrt(n)) + floor(sqrt(n-1)) - 2.

LINKS

FORMULA

a(n) = card{j>=1, A006446(j)<=n}.

MATHEMATICA

Accumulate[Boole[Table[IntegerQ[n/Floor[n^(1/2)]], {n, 1, 70}]]] (* Geoffrey Critzer, May 25 2013 *)

PROG

(PARI) a(n)=sum(k=1, n, if(k%sqrtint(k), 0, 1));

CROSSREFS

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Jan 14 2012

EXTENSIONS

Corrected by Geoffrey Critzer, May 25 2013

STATUS

approved