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%I #9 Jul 13 2013 12:04:27
%S 17,26,29,31,33,35,38,42,44,49,50,51,52,57,58,60,62,64,65,68,70,72,73,
%T 77,78,79,81,84,85,88,89,91,95,99,100,102,103,105,106,107,110,112,114,
%U 116,119,120,121,124,125,126,128,129,130,132,135,142,143,144,146,147,150,154,156,160,162,170,175,177,178,180,182,184,192,195,196,197,202,204,205
%N Numbers n such that A212813(n) = 4.
%D Bellamy, O. S.; Cadogan, C. C. Subsets of positive integers: their cardinality and maximality properties. Proceedings of the Tenth Southeastern Conference on Combinatorics, Graph Theory and Computing (Florida Atlantic Univ., Boca Raton, Fla., 1979), pp. 167--178, Congress. Numer., XXIII-XXIV, Utilitas Math., Winnipeg, Man., 1979. MR0561043 (82b:10006)
%H Reinhard Zumkeller, <a href="/A212909/b212909.txt">Table of n, a(n) for n = 1..10000</a>
%o (Haskell)
%o import Data.List (elemIndices)
%o a212909 n = a212909_list !! (n-1)
%o a212909_list = map (+ 1) $ elemIndices 4 a212813_list
%o -- _Reinhard Zumkeller_, May 30 2012
%Y Cf. A212813, A212814, A212815, A212816, A212908.
%K nonn,fini
%O 1,1
%A _N. J. A. Sloane_, May 30 2012