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A247780 Numbers k such that A247778(k+1) - A247778(k) = 2.

%I A247780 #4 Sep 25 2014 21:16:11
%S A247780 2,5,8,10,13,16,19,22,24,27,30,33,35,38,41,44,47,49,52,55,58,61,63,66,
%T A247780 69,72,74,77,80,83,86,88,91,94,97,100,102,105,108,111,113,116,119,122,
%U A247780 125,127,130,133,136,138,141,144,147,150,152,155,158,161,164
%N A247780 Numbers k such that A247778(k+1) - A247778(k) = 2.
%C A247780 Complement of A247779.
%H A247780 Clark Kimberling, <a href="/A247780/b247780.txt">Table of n, a(n) for n = 1..1000</a>
%e A247780 The values of e - (1 + 1/k)^k for k = 1..8 are approximately 0.718282, 0.468282, 0.347911, 0.276876, 0.229962, 0.196655, 0.171782, 0.152497, so that the first 6 terms of A247778 are 1,2,4,5,6,8, and the first three terms of A247780 are 1,3,4.
%t A247780 z = 600; f[n_] := f[n] = Select[Range[z], E - (1 + 1/#)^# < 1/n &, 1];
%t A247780 u = Flatten[Table[f[n], {n, 1, z}]]       (*A247778*)
%t A247780 d1 = Flatten[Position[Differences[u], 1]] (*A247779*)
%t A247780 d2 = Flatten[Position[Differences[u], 2]] (*A247780*)
%Y A247780 Cf. A247778, A247779.
%K A247780 nonn,easy
%O A247780 1,1
%A A247780 _Clark Kimberling_, Sep 23 2014