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%I #20 Jan 24 2016 23:46:26
%S 1,2,4,7,8,12,14,15,16,21,24,26,27,29,30,31,32,38,42,45,47,48,51,53,
%T 54,56,57,58,60,61,62,63,64,71,76,80,83,85,86,90,93,95,96,99,101,102,
%U 104,105,106,109,111,112,114,115,116,118,119,120,121,123,124,125,126,127
%N Elements of A004001 that repeat consecutively.
%C Complement of A088359; A051135(a(n)) > 1. [_Reinhard Zumkeller_, Jun 03 2011]
%C From _Antti Karttunen_, Jan 18 2016: (Start)
%C This set of numbers is closed with respect to A004001, see A266188.
%C After 1, one more than the positions of zeros in A093879.
%C (End)
%H Reinhard Zumkeller, <a href="/A087686/b087686.txt">Table of n, a(n) for n = 1..10000</a>
%F Other identities. For all n >= 1:
%F A080677(a(n)) = n. [See comments in A080677.]
%t Conway[n_Integer?Positive] := Conway[n] =Conway[Conway[n-1]] + Conway[n - Conway[n-1]] Conway[1] = Conway[2] = 1 digits=1000 a=Table[Conway[n], {n, 1, digits}]; b=Table[If[a[[n]]-a[[n-1]]==0, a[[n]], 0], {n, 2, digits}]; c=Delete[Union[b], 1]
%o (Haskell)
%o import Data.List (findIndices)
%o a087686 n = a087686_list !! (n-1)
%o a087686_list = map succ $ findIndices (> 1) a051135_list
%o -- _Reinhard Zumkeller_, Jun 03 2011
%o (Scheme, with Antti Karttunen's IntSeq-library)
%o (define A087686 (MATCHING-POS 1 1 (lambda (n) (> (A051135 n) 1))))
%o ;; _Antti Karttunen_, Jan 18 2016
%Y Cf. A004001, A051135, A093879.
%Y Cf. A088359 (complement), A188163 (almost complement).
%Y Cf. A080677 (the least monotonic left inverse).
%Y Cf. also A266188, A265901, A265903, A267110, A267111, A267112.
%K nonn
%O 1,2
%A _Roger L. Bagula_, Sep 27 2003
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