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%I #14 Oct 11 2019 16:45:33
%S 1,1,2,3,4,5,8,15,14,11,16,29,32,55,58,63,64,125,128,251,246,239,256,
%T 509,508,479,510,503,512,1017,1024,2047,2030,1983,2036,2045,2048,3967,
%U 4062,4091,4096,8181,8192,16367,16378,16127,16384,32765,32760,32763
%N a(n) = 1 + sum{p=primes<n, p does not divide n} a(p).
%C a(prime(k)) = 2^(k-1). - _Ivan Neretin_, May 01 2016
%H Ivan Neretin, <a href="/A112479/b112479.txt">Table of n, a(n) for n = 1..1001</a>
%e a(9) = 1 + a(2) + a(5) + a(7), since 2, 5 and 7 are the primes < 9 and coprime to 9. So a(9) = 1 + 1 + 4 + 8
%e = 14.
%t f[l_] := Block[{n}, n = Length[l] + 1; Return[Append[l, 1 + Plus @@ l[[Select[Range[n - 1], PrimeQ[ # ] && Mod[n, # ] > 0 &]]]]];]; Nest[f, {1}, 50] (* _Ray Chandler_, Dec 26 2005 *)
%o (PARI) a(n)=if(n<7, max(n-1,1), my(s=1); forprime(p=2,n-1, if(n%p, s+=a(p))); s) \\ _Charles R Greathouse IV_, May 02 2016
%K nonn
%O 1,3
%A _Leroy Quet_, Dec 13 2005
%E Extended by _Ray Chandler_, Dec 26 2005
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