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A191857 Second factor in happy factorization of n-th rhombic number.

%I A191857 #13 Feb 28 2020 22:10:48
%S A191857 3,1,4,11,5,19,1,6,27,1,2,7,20,43,1,8,51,59,9,67,1,3,1,10,83,29,22,7,
%T A191857 2,11,1,52,107,23,1,12,123,1,2,131,5,4,139,13,1,38,53,2,163,1,14,171,
%U A191857 25,8,179,187,1,2,15,1,100,26,211,5,54,3,1,16,227,77
%N A191857 Second factor in happy factorization of n-th rhombic number.
%C A191857 a(n) = A007967(A007970(n)) = A007970(n) / A191856(n);
%C A191857 (A191856(n), a(n)) is a 2-happy couple;
%C A191857 notation: E in the Conway link.
%H A191857 Reinhard Zumkeller, <a href="/A191857/b191857.txt">Table of n, a(n) for n = 1..99</a>
%H A191857 J. H. Conway, <a href="http://www.cs.uwaterloo.ca/journals/JIS/happy.html">On Happy Factorizations</a>, J. Integer Sequences, Vol. 1, 1998, #1.
%o A191857 (Haskell)
%o A191857 a191857 = a007967 . a007970  -- _Reinhard Zumkeller_, Oct 11 2015
%Y A191857 Cf. A007967, A007970, A191856.
%K A191857 nonn
%O A191857 1,1
%A A191857 _Reinhard Zumkeller_, Jun 18 2011
%E A191857 Wrong formula removed (thanks to _Wolfdieter Lang_, who pointed this out), by _Reinhard Zumkeller_, Oct 11 2015