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A072938 Highly composite numbers that are half of the next highly composite number. 12


%S 1,2,6,12,60,360,2520

%N Highly composite numbers that are half of the next highly composite number.

%C A002182(k) such that A002182(k+1) = 2*A002182(k).

%C Numbers m such that d(m)>=d(k) for 0<k<2m {d(n) being the number of divisors function: A000005(n)}. - _Lekraj Beedassy_, Dec 16 2004

%C W. Brefeld (cf. link) gives a proof that there are no other terms. - _Klaus Brockhaus_, Mar 05 2006

%H Werner Brefeld, <a href="http://www.brefeld.homepage.t-online.de/teilbarkeit.html">Ramanujan, zusammengesetzte Zahlen und ihre Teilbarkeit</a>

%H Achim Flammenkamp <a href="http://www.uni-bielefeld.de/~achim/highly.html">Highly Composite Numbers</a>

%e 6 = A002182(4) is a term since A002182(5) = 12 = 2*6.

%Y Cf. A002182, A002201, A106037, A094348, A003418, A002110.

%Y A165412. - _Reinhard Zumkeller_, Jan 20 2010

%K nonn,fini,full

%O 1,2

%A Anon, Aug 12 2002

%E Edited by _Klaus Brockhaus_, Aug 13 2002

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Last modified February 13 10:22 EST 2016. Contains 268262 sequences.