|
Search: id:A066388
|
|
|
| A066388 |
|
Numbers n such that n and 2n are both between a pair of twin primes. |
|
+0
6
|
|
| 6, 30, 660, 810, 2130, 2550, 3330, 3390, 5850, 6270, 10530, 33180, 41610, 44130, 53550, 55440, 57330, 63840, 65100, 70380, 70980, 72270, 74100, 74760, 78780, 80670, 81930, 87540, 93240, 102300, 115470, 124770, 133980, 136950, 156420
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Also terms of A014574 such that twice the term is also in A014574. Related to a problem of anti-divisors.
A117499(a(n)) = 4. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Mar 23 2006
|
|
LINKS
|
Eric Weisstein's World of Mathematics, Bitwin Chain
|
|
EXAMPLE
|
For n=30, 29 and 31 are prime, as are 59 and 61.
|
|
MATHEMATICA
|
lst={}; Do[p1=Prime[n]; p2=Prime[n+1]; d=2; If[p2-p1==d, w=p1+1; If[PrimeQ[2*w-1]&&PrimeQ[2*w+1], AppendTo[lst, w]]], {n, 1, 10^4}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 07 2008]
|
|
CROSSREFS
|
Cf. A001359, A006512, A012574.
Sequence in context: A119634 A075591 A130075 this_sequence A088256 A136349 A119411
Adjacent sequences: A066385 A066386 A066387 this_sequence A066389 A066390 A066391
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Jud McCranie (j.mccranie(AT)comcast.net), Dec 23 2001
|
|
|
Search completed in 0.002 seconds
|
