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A175728 Decimal expansion of e written as a sequence of distinct positive integers.

%I A175728 #11 Apr 01 2022 11:40:07
%S A175728 2,7,1,8,28,18,284,5,90,4,52,3,53,60,287,47,13,526,6,24,9,77,57,2470,
%T A175728 93,69,99,59,574,96,696,76,27,72,40,766,30,35,354,75,94,571,38,21,78,
%U A175728 525,16,64,274,2746,63,91,93200,305,992,181,74,135,966,290,43,572,900,33,42
%N A175728 Decimal expansion of e written as a sequence of distinct positive integers.
%C A175728 Inverse: 3, 1, 12, 10, 8, 19, 2, 4, 21, 119, 86, 166, 17, 154, 160, 47, 192, 6, 83, 214, ..., . - _Robert G. Wilson v_, Aug 22 2010
%H A175728 Michael S. Branicky, <a href="/A175728/b175728.txt">Table of n, a(n) for n = 1..10000</a>
%t A175728 rd = RealDigits[E, 10, 200][[1]]; lst = {}; f[n_] := Block[{k = 1}, While[a = FromDigits[ Take[ rd, k]]; MemberQ[lst, a] || rd[[k + 1]] == 0, k++ ]; AppendTo[ lst, a]; rd = Drop[rd, k]]; Array[f, 70]; lst (* _Robert G. Wilson v_, Aug 22 2010 *)
%o A175728 (Python)
%o A175728 from itertools import islice
%o A175728 from sympy import exp
%o A175728 def diggen():
%o A175728     yield from map(int, str(exp(1).n(10**5))[:-1].replace(".", ""))
%o A175728 def agen(): # generator of terms
%o A175728     g = diggen()
%o A175728     aset, nextd = set(), next(g)
%o A175728     while True:
%o A175728         an, nextd = nextd, next(g)
%o A175728         while an in aset or nextd == 0:
%o A175728             an, nextd = int(str(an) + str(nextd)), next(g)
%o A175728         yield an
%o A175728         aset.add(an)
%o A175728 print(list(islice(agen(), 65))) # _Michael S. Branicky_, Mar 31 2022
%Y A175728 Cf. A001113, A064809.
%K A175728 nonn,base
%O A175728 1,1
%A A175728 _Jason G. Wurtzel_, Aug 19 2010
%E A175728 More terms from _Robert G. Wilson v_, Aug 22 2010