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%I #24 May 09 2021 05:03:23
%S 1,5,10,4,11,3,12,2,13,25,38,24,9,25,8,26,7,27,6,28,51,75,50,76,49,21,
%T 50,20,51,19,52,18,53,17,54,16,55,15,56,14,57,101,146,100,147,99,148,
%U 98,47,99,46,100,45,101,44,102,43,103,42,104,41,105,40,106,39,107,176
%N a(1) = 1; for n > 1, a(n) = a(n-1)-(n+2) if this is positive and has not already appeared, otherwise a(n) = a(n-1)+(n+2).
%H Robert Israel, <a href="/A066200/b066200.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Rea#Recaman">Index entries for sequences related to Recamán's sequence</a>
%p S:= {1}:
%p a[1]:= 1:
%p for n from 2 to 100 do
%p t:=a[n-1]-(n+2);
%p if t > 0 and not member(t,S) then
%p a[n]:= t
%p else
%p a[n]:= a[n-1]+(n+2)
%p fi;
%p S:= S union {a[n]}
%p od:
%p seq(a[n],n=1..100); # _Robert Israel_, Feb 10 2017
%o (Python)
%o l=[0, 1]
%o for n in range(2, 101):
%o x=l[n - 1] - (n + 2)
%o if x>0 and x not in l: l.append(x)
%o else: l.append(l[n - 1] + (n + 2))
%o print(l[1:]) # _Indranil Ghosh_, Jun 02 2017
%Y A variant of A005132. A row of the array in A066201.
%K nonn,easy,look
%O 1,2
%A _N. J. A. Sloane_, Dec 16 2001
%E More terms from _Vladeta Jovovic_, Dec 16 2001
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