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A072938 Highly composite numbers that are half of the next highly composite number. 12
1, 2, 6, 12, 60, 360, 2520 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

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

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

W. Brefeld (cf. link) gives a proof that there are no other terms. - Klaus Brockhaus, Mar 05 2006

LINKS

Table of n, a(n) for n=1..7.

Werner Brefeld, Ramanujan, zusammengesetzte Zahlen und ihre Teilbarkeit.

Achim Flammenkamp, Highly Composite Numbers.

EXAMPLE

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

CROSSREFS

Cf. A002110, A002182, A002201, A003418, A094348, A106037, A165412.

Sequence in context: A254232 A189394 A182862 * A160274 A048803 A068625

Adjacent sequences:  A072935 A072936 A072937 * A072939 A072940 A072941

KEYWORD

nonn,fini,full

AUTHOR

Anon, Aug 12 2002

EXTENSIONS

Edited by Klaus Brockhaus, Aug 13 2002

STATUS

approved

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Last modified October 20 04:37 EDT 2019. Contains 328247 sequences. (Running on oeis4.)