A129382 a(0)=1. a(n) = the number of earlier terms which are coprime to floor(sqrt(n)).

1, 1, 2, 3, 3, 4, 4, 4, 4, 7, 8, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 16, 17, 18, 19, 20, 20, 20, 20, 20, 20, 20, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 48, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 27, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28, 28

Offset

0,3

Links

Table of n, a(n) for n=0..79.

Example

Floor(sqrt(11)) = 3. So a(11) is the number of terms from among a(0),a(1),...a(10) which are coprime to 3. Every term from a(0) through a(10), with the exception of a(3) and a(4), is coprime to 3; so a(11) = 9.

Maple

a[0]:=1: for n from 1 to 100 do ct:=0: for j from 0 to n-1 do if igcd(a[j], floor(sqrt(n)))=1 then ct:=ct+1 else fi: od: a[n]:=ct: od: seq(a[n], n=0..100); # Emeric Deutsch, Apr 16 2007

Crossrefs

Cf. A129381.

Sequence in context: A357815 A221983 A029118 * A353241 A163515 A220348

Adjacent sequences: A129379 A129380 A129381 * A129383 A129384 A129385

Keyword

nonn

Author

Leroy Quet, Apr 12 2007

Extensions

More terms from Emeric Deutsch, Apr 16 2007

Status

approved