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%I #14 May 11 2020 18:46:43
%S 1,1,2,2,4,5,6,3,6,8,10,8,12,13,12,5,16,12,18,16,20,21,22,15,19,24,16,
%T 26,28,24,30,9,31,33,32,21,36,36,36,33,40,38,42,40,36,45,46,25,44,39,
%U 50,48,52,29,50,51,54,56,58,47,60,60,57,21,60,61,66,66,67,63,70,37,72,72
%N a(n) = number of earlier terms which are not divisible by the largest prime dividing n, for n >= 2, with a(1) = 1.
%F a(p) = p - 1 for p prime. - _Petros Hadjicostas_, May 11 2020
%e 3 is the largest prime dividing 12. Among the first 11 terms of the sequence there are 8 terms (1, 1, 2, 2, 4, 5, 8, 10) that are not divisible by 3. So a(12) = 8.
%t f[s_] := Append[s, Length@ Select[s, Mod[ #, FactorInteger[1 + Length@s] [[ -1, 1]]] != 0 &]]; Nest[f, {1}, 76] (* _Robert G. Wilson v_ *)
%o (PARI) {m=75;print1(a=1,",");v=[a];for(n=2,m,f=factor(n);p=f[matsize(f)[1],1];a=0;for(j=1,n-1,if(v[j]%p>0,a++));print1(a,",");v=concat(v,a))} \\ _Klaus Brockhaus_, Aug 15 2006
%Y Cf. A096216, A121599.
%K nonn
%O 1,3
%A _Leroy Quet_, Aug 09 2006
%E More terms from _Klaus Brockhaus_ and _Robert G. Wilson v_, Aug 15 2006
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