cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A039773 phi(n) is equal to the sum of prime factors and exponents of n-1.

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%I A039773 #7 Mar 27 2017 08:41:14
%S A039773 5,34,66,130,490,18130
%N A039773 phi(n) is equal to the sum of prime factors and exponents of n-1.
%e A039773 phi(34)=16, 33=3^1*11^1, 3+1+11+1=16.
%t A039773 Select[Range[20000],Total[Flatten[FactorInteger[#-1]]]==EulerPhi[#]&] (* _Harvey P. Dale_, Mar 27 2017 *)
%Y A039773 Cf. A000010, A008474.
%K A039773 nonn
%O A039773 1,1
%A A039773 _Olivier Gérard_
%E A039773 Next term if it exists is >= 5*10^7 - _Naohiro Nomoto_, Jun 24 2001.