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.
%I A217619 #9 Oct 12 2012 13:39:26 %S A217619 2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2, %T A217619 5,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2,2, %U A217619 2,5,2,2,2,2,3,2,2,2,2,3,2,2,2,2,3,2,2 %N A217619 a(n) = m/(12*n) where m is the least multiple of n that satisfies phi(m) = phi(m+6*n). %C A217619 It appears that A217140(n) is divisible by 12 for all n. %H A217619 S. W. Graham, J. J. Holt and C. Pomerance, <a href="http://www.math.dartmouth.edu/~carlp/phi.pdf">On the solutions to phi(n) = phi(n+k)</a>, Number Theory in Progress, K. Gyory, H. Iwaniec, and J. Urbanowicz, eds., vol. 2, de Gruyter, Berlin and New York, 1999, pp. 867-882. %F A217619 a(n) = A217140(n)/12. %e A217619 A179188(1)=24 is divisible by 1 and the quotient 24 when divided by 12 gives 2, so a(1)=2. %e A217619 A217139(1)=48 is divisible by 2 and the quotient 24 when divided by 12 gives 2, so a(2)=2. %e A217619 A217140(5)=36 and 36/12=3, so a(5)=3. %Y A217619 Cf. A179188, A217139, A217141, A217068, A217140. %K A217619 nonn %O A217619 1,1 %A A217619 _Jonathan Sondow_ and _Michel Marcus_, Oct 09 2012