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 A130499 a(1)=1. a(n) = number of earlier terms of the sequence which are coprime to (the sum of positive integers which are <=n and missing from first (n-1) terms of sequence). 2

%I

%S 1,1,2,3,3,3,5,6,6,6,10,5,7,13,14,6,9,17,18,5,7,13,13,7,13,13,8,27,24,

%T 25,30,19,30,15,29,17,36,22,19,15,40,41,16,39,38,24,28,28,48,39,29,30,

%U 50,34,30,30,55,31,25,25,30,61,44,29,27,37,38,36,65,28,63,38,45,28,54

%N a(1)=1. a(n) = number of earlier terms of the sequence which are coprime to (the sum of positive integers which are <=n and missing from first (n-1) terms of sequence).

%H Diana Mecum, <a href="/A130499/b130499.txt">Table of n, a(n) for n=1,...,569</a>

%e The positive integers which are <= 9 and are missing from the first 8 terms of the sequence are 4,7,8,9. The sum of these integers is 28, so a(9) is the number of earlier terms which are coprime to 28. Therefore a(9) = 6.

%Y Cf. A130498.

%K nonn

%O 1,3

%A _Leroy Quet_, May 31 2007

%E Added terms a(12) - a(569) _Diana L. Mecum_, Jan 01 2009

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Last modified June 19 15:01 EDT 2021. Contains 345140 sequences. (Running on oeis4.)