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 A216387 #26 May 19 2024 02:10:29
%S A216387 1,2,2,16,57,325,1666,9787,58979,366329
%N A216387 Number of values of k for which phi(k) is a permutation of decimal digits of k, for 10^(n-1) < k < 10^n.
%F A216387 a(n) = # { k in A115921 | 10^(n-1) < k < 10^n }. - _M. F. Hasler_, Feb 24 2014
%e A216387 a(3) = 2 because the values of k satisfying the condition for 10^2 < k < 10^3 are {291, 502}. - _V. Raman_, Feb 17 2014
%o A216387 (PARI) a(n)=sum(k=10^(n-1), 10^n, vecsort(digits(k)) == vecsort(digits(eulerphi(k)))) \\ _V. Raman_, Feb 17 2014, based on edits by _M. F. Hasler_
%Y A216387 Cf. A000010 (phi), A115921.
%K A216387 nonn,base,more
%O A216387 1,2
%A A216387 _V. Raman_, Sep 06 2012
%E A216387 a(9)-a(10) from _Amiram Eldar_, May 19 2024