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A133017 Decimal expansion of the constant formed by concatenating the imperfect numbers. 0

%I

%S 1,2,3,4,5,7,8,9,1,0,1,1,1,2,1,3,1,4,1,5,1,6,1,7,1,8,1,9,2,0,2,1,2,2,

%T 2,3,2,4,2,5,2,6,2,7,2,9,3,0,3,1,3,2,3,3,3,4,3,5,3,6,3,7,3,8,3,9,4,0,

%U 4,1,4,2,4,3,4,4,4,5

%N Decimal expansion of the constant formed by concatenating the imperfect numbers.

%C A theorem of Copeland & Erdős proves that this constant is 10-normal. - _Charles R Greathouse IV_, Feb 06 2015

%H A. H. Copeland and P. Erdős, <a href="http://www.renyi.hu/~p_erdos/1946-01.pdf">Note on normal numbers</a>, Bull. Amer. Math. Soc. 52 (1946), pp. 857-860.

%e 0.12345789101112131415161718192021222324252627293031...

%o (PARI) print1(1); for(n=2, 45, if(sigma(n,-1)!=2, d=digits(n); for(i=1, #d, print1(", "d[i])))) \\ _Charles R Greathouse IV_, Feb 06 2015

%Y Cf. A007376, A033307, A033308, A079718. Imperfect numbers: A132999.

%K cons,easy,nonn,base

%O 0,2

%A _Omar E. Pol_, Oct 20 2007

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Last modified April 11 05:18 EDT 2021. Contains 342886 sequences. (Running on oeis4.)