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A118065 a(1) = a(2) = 1, a(n) = smallest number greater than a(n-1) that can be written as sum of consecutive earlier terms.

%I A118065 #6 Jul 23 2025 22:48:48
%S A118065 1,1,2,3,4,5,6,7,9,10,11,12,13,14,15,16,18,19,20,21,22,23,25,26,27,28,
%T A118065 29,30,31,32,33,34,36,37,38,39,41,42,43,44,45,46,47,48,49,50,51,52,53,
%U A118065 54,55,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,73,74,75,76,77,78
%N A118065 a(1) = a(2) = 1, a(n) = smallest number greater than a(n-1) that can be written as sum of consecutive earlier terms.
%C A118065 Complement of A118066.
%H A118065 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HofstadterSequences.html">Hofstadter Sequences</a>
%e A118065 a(20) = a(11) + a(10) = 11 + 10 = 21;
%e A118065 a(21) = a(9) + a(8) + a(7) = 9 + 7 + 6 = 22;
%e A118065 a(22) = a(12) + a(11) = 12 + 11 = 23;
%e A118065 a(23) = a(13) + a(12) = 13 + 12 = 25;
%e A118065 a(24) = a(10) + a(9) + a(8) = 10 + 9 + 7 = 26.
%Y A118065 Cf. A005243, A118066.
%K A118065 nonn
%O A118065 1,3
%A A118065 _Reinhard Zumkeller_, Apr 11 2006