A171743 a(n) = A000010(A001043(n)).
4, 4, 4, 6, 8, 8, 12, 12, 24, 16, 32, 24, 24, 24, 40, 48, 32, 64, 44, 48, 72, 54, 84, 60, 60, 64, 48, 72, 72, 64, 84, 132, 88, 96, 80, 120, 128, 80, 128, 160, 96, 120, 128, 96, 120, 160, 180, 120, 144, 120, 232, 128, 160, 252, 192, 216, 144, 272, 180, 184, 192, 160
Offset: 1
Programs
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Maple
A000010 := proc(n) numtheory[phi](n); end proc: A001043 := proc(n) ithprime(n)+ithprime(n+1) ; end proc: A171743 := proc(n) A000010(A001043(n)) ; end proc: for n from 1 to 100 do printf("%d,", A171743(n)) ; od: # R. J. Mathar, Jan 21 2010
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Mathematica
EulerPhi[Total[#]]&/@Partition[Prime[Range[70]],2,1] (* Harvey P. Dale, Mar 05 2013 *)
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PARI
p=2;forprime(q=3,1e3,print1((p-1)*(q-1)", ");p=q) \\ Charles R Greathouse IV, Feb 21 2013
Formula
a(n) = phi(prime(n) + prime(n+1)).
Extensions
Corrected (a(36)=204 removed) by R. J. Mathar, Jan 21 2010