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A047841 Autobiographical numbers: Fixed under operator T (A047842): "Say what you see". 24

%I #23 Dec 19 2017 18:35:19

%S 22,10213223,10311233,10313314,10313315,10313316,10313317,10313318,

%T 10313319,21322314,21322315,21322316,21322317,21322318,21322319,

%U 31123314,31123315,31123316,31123317,31123318,31123319

%N Autobiographical numbers: Fixed under operator T (A047842): "Say what you see".

%C A digit count numerically summarizes the frequency of digits 0 through 9 in that order when they occur in a number.

%C This uses a different method from A108810. Here the digits are described in increasing order, whereas in A108810 they can be described in any order.

%C This sequence is finite, since T(x) < x for every x with at least 22 digits. Last term is a(109) = 101112213141516171819. - Schimke

%C A character in the Verghese (2009) novel declares that 10213223 "is the only number that describes itself when you read it." - _Alonso del Arte_, Jan 26 2014

%D J. N. Kapur, Reflections of a Mathematician, Chapter 33, pp. 314-318, Arya Book Depot, New Delhi 1996.

%D Abraham Verghese, Cutting for Stone: A Novel. New York: Alfred A. Knopf (2009): 294.

%H David Wasserman, <a href="/A047841/b047841.txt">Table of n, a(n) for n = 1..109</a> (full sequence)

%H Andre Kowacs, <a href="https://arxiv.org/abs/1708.06452">Studies on the Pea Pattern Sequence</a>, arXiv:1708.06452 [math.HO], 2017.

%e 10313314 contains 1 0's, 3 1's, 3 3's and 1 4's, hence T(10313314) = 10313314 is in the sequence

%e The entry 3122331418, for instance, is a member since it is indeed made up of three 1's, two 2's, three 3's, one 4 and one 8.

%Y Cf. A005151, which is the sequence 1, T(1), T(T(1)), .. ending in the fixed-point 21322314.

%Y Cf. A104785, A104786, A104787, A108810.

%K nonn,fini,full,base,nice,eigen

%O 1,1

%A Ulrich Schimke (ulrschimke(AT)aol.com)

%E Entry revised by _N. J. A. Sloane_, Dec 15 2006

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Last modified May 17 15:30 EDT 2024. Contains 372603 sequences. (Running on oeis4.)