A129381 - OEIS

A129381

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

1, 1, 2, 2, 2, 2, 2, 2, 8, 9, 9, 9, 9, 9, 9, 8, 8, 8, 8, 8, 8, 8, 8, 8, 24, 25, 25, 25, 25, 25, 25, 25, 25, 25, 25, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 48, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..77.

EXAMPLE

Floor(sqrt(11)) = 3. So a(11) is the number of terms from among a(1),a(2),...a(10) which are coprime to 3. Terms a(1) through a(9) are each coprime to 3, so a(11) = 9.

MAPLE

a[1]:=1: for n from 2 to 100 do ct:=0: for j from 1 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=1..100); # Emeric Deutsch, Apr 16 2007

CROSSREFS

Cf. A129382.

Sequence in context: A299150 A202448 A339165 * A319991 A323275 A139514

Adjacent sequences: A129378 A129379 A129380 * A129382 A129383 A129384

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 12 2007

EXTENSIONS

More terms from Emeric Deutsch, Apr 16 2007

STATUS

approved