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%I #26 Mar 02 2020 09:18:19
%S 1,1,5,10,47,200,842,4698,28831
%N Number of values of k for which sigma(k) is a permutation of decimal digits of k, for 10^(n-1) < k < 10^n.
%F a(n) = # { k in A115920 | 10^(n-1) < k < 10^n }. - _M. F. Hasler_, Feb 24 2014
%e a(3) = 5 because the values of k satisfying the condition for 10^2 < k < 10^3 are {258, 270, 276, 609, 639}. - _V. Raman_, Feb 18 2014
%o (PARI) a(n)=sum(k=10^(n-1), 10^n, vecsort(digits(k)) == vecsort(digits(sigma(k)))) \\ _V. Raman_, Feb 18 2014, based on edits by _M. F. Hasler_
%Y Cf. A115920, A000203.
%K nonn,base,more
%O 1,3
%A _V. Raman_, Sep 06 2012
%E a(9) from _Jinyuan Wang_, Mar 02 2020