%I A130846
%S A130846 2,3,23,4,235,35,26,347,237,58,2359,349,2610,311,235711,45712,2313,3813,
%T A130846 2614,345915,235915,716,2371017,3417,2561118,3581119,2319,41220,237921,
%U A130846 35791321,2561322,3423,23101423,824,2351525,3457111525,2671126,391627
%N A130846 Replace n by the concatenation of its anti-divisors.
%C A130846 Number of anti-divisors concatenated to form a(n) is A066272(n). We may 
               consider prime values of the concatenated anti-divisor sequence and 
               we may iterate it, i.e. n, a(n), a(a(n)), a(a(a(n))) which leads 
               to questions of trajectory, cycles, fixed points.
%C A130846 See A066272 for definition of anti-divisor.
%C A130846 Primes in this sequence are at n=3,4,5,10,14,16,40,46,100,145,149,... 
               - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 24 2007
%H A130846 Jon Perry, <a href="a066272a.html">The Anti-Divisor</a>, cached copy.
%H A130846 J. V. Post, <a href="a130846.txt">Factors of first 62 terms</a>
%e A130846 3: 2, so a(3) = 2.
%e A130846 4: 3, so a(4) = 3.
%e A130846 5: 2, 3, so a(5) = 23.
%e A130846 6: 4, so a(6) = 4.
%e A130846 7: 2, 3, 5, so a(7) = 235.
%e A130846 17: 2, 3, 5, 7, 11, so a(17) = 235711
%p A130846 antiDivs := proc(n) local resul,odd2n,r ; resul := {} ; for r in ( numtheory[divisors](2*n-1) 
               union numtheory[divisors](2*n+1) ) do if n mod r <> 0 and r> 1 and 
               r < n then resul := resul union {r} ; fi ; od ; odd2n := numtheory[divisors](2*n) 
               ; for r in odd2n do if ( r mod 2 = 1) and r > 2 then resul := resul 
               union {2*n/r} ; fi ; od ; RETURN(resul) ; end: A130846 := proc(n) 
               cat(op(antiDivs(n))) ; end: seq(A130846(n),n=3..80) ; - R. J. Mathar 
               (mathar(AT)strw.leidenuniv.nl), Jul 24 2007
%Y A130846 Cf. A037278, A066272, A120712, A106708, A130799.
%Y A130846 Sequence in context: A137077 A046965 A119679 this_sequence A114101 A114007 
               A071819
%Y A130846 Adjacent sequences: A130843 A130844 A130845 this_sequence A130847 A130848 
               A130849
%K A130846 base,easy,nonn
%O A130846 3,1
%A A130846 Jonathan Vos Post (jvospost3(AT)gmail.com), Jul 20 2007, Jul 22 2007
%E A130846 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 24 2007