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%I #7 Jul 13 2013 12:04:14
%S 1,2,4,6,7,9,11,12,13,15,17,18,20,22,23,25,27,29,30,32,34,35,37,39,41,
%T 42,44,46,47,49,51,52,54,56,58,59,61,63,64,66,68,70,71,73,75,76,78,80,
%U 81,82,84,86,87,89,91,92,94,96,98,99,101,103,104,106,108
%N Positions of triangular numbers (A000217) in the union of squares and triangular numbers (A005214).
%C A010054(A005214(a(n))) = 1.
%H Reinhard Zumkeller, <a href="/A193715/b193715.txt">Table of n, a(n) for n = 1..10000</a>
%o (Haskell)
%o import Data.List (elemIndex)
%o import Data.Maybe (fromJust)
%o a193715 n = a193715_list !! (n-1)
%o a193715_list =
%o map ((+ 1) . fromJust . (`elemIndex` a005214_list)) $ tail a000217_list
%Y Cf. A193714.
%K nonn
%O 1,2
%A _Reinhard Zumkeller_, Aug 03 2011