A076641 - OEIS

%I #8 Dec 09 2020 18:49:00

%S 0,1,2,3,4,5,6,7,8,9,11,21,31,41,51,61,71,81,91,12,22,32,42,52,62,72,

%T 82,92,13,23,33,43,53,63,73,83,93,14,24,34,44,54,64,74,84,94,15,25,35,

%U 45,55,65,75,85,95,16,26,36,46,56,66,76,86,96,17,27,37,47,57,67,77,87,97

%N Integers read backwards, but with repetitions omitted.

%C Although this is a list, it seems most natural here to have offset 0. - _N. J. A. Sloane_, Dec 09 2020

%H Reinhard Zumkeller, <a href="/A076641/b076641.txt">Table of n, a(n) for n = 0..10000</a>

%H Dana G. Korssjoen, Biyao Li, Stefan Steinerberger, Raghavendra Tripathi, and Ruimin Zhang, <a href="https://arxiv.org/abs/2012.04625">Finding structure in sequences of real numbers via graph theory: a problem list</a>, arXiv:2012.04625, Dec 08, 2020

%e 10 backwards is 01=1, but 1 already appears, so omit it.

%p s := (L::list)->sum(L[i]*10^(nops(L)-i),i=1..nops(L)); d := (X::posint)->convert(X,base,10); SD := K->[seq(s(d(k)),k=1..K)];

%o (Haskell)

%o a076641 = a004086 . a067251  -- _Reinhard Zumkeller_, Aug 12 2013

%Y Cf. A004086.

%K easy,nonn,base

%O 0,3

%A Francois Jooste (phukraut(AT)hotmail.com), Oct 23 2002

%E a(0) = 0 added by _N. J. A. Sloane_, Dec 09 2020