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%I #12 Aug 24 2015 02:20:59
%S 1,1,2,3,3,5,4,7,6,9,9,11,9,10,14,13,16,11,12,7,20,14,15,23,16,17,26,
%T 25,28,21,21,31,20,27,18,35,22,29,18,39,37,41,26,26,26,26,46,44,48,26,
%U 35,27,17,18,54,46,56,29,30,50,25,25,62,32,54,26,66,46,56,38,70,67,72,33
%N a(1)=1. a(n) = number of earlier terms of {a(k)} that are coprime to A130158(n-1).
%C Note that A130158 is a list of the positive divisors of the terms of this sequence.
%e {a(k)} begins: 1,1,2,3,3,5,4,... So sequence A130158 begins: 1,1,1,2,1,3,1,3,1,5,1,2,4,... So for example, a(7) is the number of terms from among (1,1,2,3,3,5) which are coprime to A130158(6) = 3. Therefore a(7) = 4.
%p A130157 := proc(nmax) local a,a130158,n,anext,i ; a := [1] ; a130158 := [] ; while nops(a) < nmax do n := nops(a)+1 ; a130158 := [op(a130158),op(numtheory[divisors](op(-1,a)))] ; anext :=0 ; for i from 1 to nops(a) do if gcd(op(i,a),op(n-1,a130158)) = 1 then anext := anext+1 ; fi ; od ; a := [op(a),anext] ; od ; RETURN(a) ; end: A130157(80) ; # _R. J. Mathar_, Jun 12 2007
%Y Cf. A130158.
%K nonn
%O 1,3
%A _Leroy Quet_, May 13 2007
%E More terms from _R. J. Mathar_, Jun 12 2007
%E Edited by _Charles R Greathouse IV_, Apr 27 2010
%E Edited by _N. J. A. Sloane_, May 09 2010
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