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 A216392 #19 Mar 29 2014 03:27:49
%S A216392 1,1,1,1,1,1,2,2,5,7,7,13,16,21,35,57,83,143,207,278,457,790,1064,
%T A216392 1815,3468,5194,8226
%N A216392 Number of values of k for which sigma(k) is a permutation of decimal digits of k, for k < 2^n.
%F A216392 a(n) = # { k in A115920 | k < 2^n }. - _M. F. Hasler_, Feb 24 2014
%e A216392 a(10) = 7 because the values of k satisfying the condition for k < 2^10 are {1, 69, 258, 270, 276, 609, 639}. - _V. Raman_, Feb 18 2014
%o A216392 (PARI) a(n)=sum(k=1, 2^n, vecsort(digits(k)) == vecsort(digits(sigma(k)))) \\ _V. Raman_, Feb 18 2014, based on edits by _M. F. Hasler_
%Y A216392 Cf. A115920, A000203.
%K A216392 nonn,base,more
%O A216392 1,7
%A A216392 _V. Raman_, Sep 06 2012