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 A079009 #21 Aug 27 2024 09:15:30 %S A079009 1,2,11,37,149,1359,14130,175327,1218073,108387730,14305141265 %N A079009 Least k such that the 2^n successive values of phi(k+j) (j=0..2^n-1) are all distinct. %F A079009 a(n) = A079008(2^n). %e A079009 For n = 7: a(7) = 175327 because phi(175327+j), for j=0..127 are all distinct: {175326, 87648, ..., 175452, 85320}. %o A079009 (PARI) isdist(v) = forstep(i = #v, 1, -1, forstep(j = i - 1, 1, -1, if(v[i] == v[j], return(j)))); 0; %o A079009 a(n) = {my(m = 2^n, phis = vector(m, i, eulerphi(i)), k = m, ind = isdist(phis)); while(ind != 0, phis = concat(vecextract(phis, Str("^1.."ind)), vector(ind, i, eulerphi(k+i))); k += ind; ind = isdist(phis)); k - m + 1;} \\ _Amiram Eldar_, Aug 27 2024 %Y A079009 Cf. A000010, A079008, A079007, A048892. %K A079009 nonn,more %O A079009 0,2 %A A079009 _Labos Elemer_, Jan 10 2003 %E A079009 a(8)-a(9) from _Donovan Johnson_, Oct 27 2008 %E A079009 a(10) from _Donovan Johnson_, Nov 13 2010