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%I #25 Jul 23 2015 22:21:39
%S 0,0,1,0,1,0,0,0,2,1,1,2,5,4,15,15,16,35,91,90,158,345,586,694,1549,
%T 2700,3363
%N Number of values of k for which sigma(k)-k is a permutation of decimal digits of k, for 2^(n-1) < k < 2^n.
%F a(n) = # { k in A085844 | 2^(n-1) < k < 2^n }. - _M. F. Hasler_, Feb 24 2014
%e a(13) = 5 because the values of k satisfying the condition for 2^12 < k < 2^13 are {4672, 4896, 5046, 7785, 8128}. - _V. Raman_, Feb 19 2014
%o (PARI) a(n)=sum(k=2^(n-1), 2^n, vecsort(digits(k)) == vecsort(digits(sigma(k)-k))) \\ _V. Raman_, Feb 19 2014, based on edits by _M. F. Hasler_
%o (Python)
%o from sympy import divisor_sigma
%o def A216396(n):
%o ....c = 0
%o ....for i in range(2**(n-1)+1,2**n):
%o ........s1, s2 = sorted(str(i)),sorted(str(divisor_sigma(i)-i))
%o ........if len(s1) == len(s2) and s1 == s2:
%o ............c += 1
%o ....return c # _Chai Wah Wu_, Jul 23 2015
%Y Cf. A085844, A001065.
%K nonn,base,more
%O 1,9
%A _V. Raman_, Sep 06 2012
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