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A115186 Smallest number m such that m and m+1 have exactly n prime factors (counted with multiplicity). 5
2, 9, 27, 135, 944, 5264, 29888, 50624, 203391, 3290624, 6082047, 32535999, 326481920, 3274208000, 6929459199, 72523096064, 37694578688, 471672487935, 11557226700800, 54386217385983, 50624737509375, 275892612890624, 4870020829413375, 68091093855502335, 2280241934368767 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A001222(a(n)) = A001222(a(n)+1) = n: subsequence of A045920;

a(16) > 4*10^10 - Martin Fuller, Jan 17 2006

a(n)  <= A093548(n) <= A052215(n). - Zak Seidov, Jan 16 2015

REFERENCES

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 135, p. 46, Ellipses, Paris 2008.

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

a(10) = 3290624 = 6427 * 2^9, 3290624+1 = 13 * 5^5 * 3^4:

A001222(3290624) = A001222(3290625) = 10.

CROSSREFS

Cf. A001222, A045920, A052215, A093548.

Sequence in context: A256233 A123904 A019065 * A243560 A090900 A155472

Adjacent sequences:  A115183 A115184 A115185 * A115187 A115188 A115189

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jan 16 2006

EXTENSIONS

a(13)-a(15) from Martin Fuller, Jan 17 2006

a(16)-a(17) from Donovan Johnson, Apr 08 2008

a(18)-a(22) from Donovan Johnson, Jan 21 2009

a(23)-a(25) from Donovan Johnson, May 25 2013

STATUS

approved

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Last modified September 24 04:27 EDT 2017. Contains 292403 sequences.