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.

A070809 Cototient(totient(n))=A070556(n) is not a power of 2 and n is not a prime number.

This page as a plain text file.
%I A070809 #4 Oct 15 2013 22:31:19
%S A070809 1,22,25,27,33,38,44,46,49,50,54,55,57,62,63,66,69,74,75,76,77,81,82,
%T A070809 86,88,91,92,93,94,95,98,99,100,106,108,110,111,114,115,117,118,121,
%U A070809 122,123,124,125,126,129,132,133,134,135,138,141,142,143,146,147,148
%N A070809 Cototient(totient(n))=A070556(n) is not a power of 2 and n is not a prime number.
%e A070809 n=95: Phi[95]=72,cototient[72]=72-phi[72]=72-24-=48 is not a power of 2.
%t A070809 Do[s= EulerPhi[n]-EulerPhi[EulerPhi[n]]; If[ !IntegerQ[Log[2, s]]&&!PrimeQ[n], Print[n]], {n, 1, 1000}]
%Y A070809 Cf. A070556, A051953, A054571, A070806, A070807, A070810, A070811.
%K A070809 nonn
%O A070809 1,2
%A A070809 _Labos Elemer_, May 08 2002