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%I #19 Mar 29 2014 03:27:49
%S 1,1,1,1,1,1,2,2,5,7,7,13,16,21,35,57,83,143,207,278,457,790,1064,
%T 1815,3468,5194,8226
%N Number of values of k for which sigma(k) is a permutation of decimal digits of k, for k < 2^n.
%F a(n) = # { k in A115920 | k < 2^n }. - _M. F. Hasler_, Feb 24 2014
%e 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 (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 Cf. A115920, A000203.
%K nonn,base,more
%O 1,7
%A _V. Raman_, Sep 06 2012
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