|
| |
|
|
A100821
|
|
a(n) = 1 if prime(n) + 2 = prime(n+1), otherwise 0.
|
|
1
| |
|
|
0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Same as A062301 except for starting point.
a(n)=1 iff prime(n) is the smaller of a pair of twin primes, else a(n)=0. This sequence can be derived from the sequence b(n)=1 iff n and n+2 are both prime, else b(n)=0. This latter sequence has as its inverse Moebius transform the sequence c(n) = the number of distinct factors of n which are the smaller of a pair of twin primes. For example, c(15)=2 because 15 is divisible by 3 and 5, each of which is the smaller of a pair of twin primes. - Jonathan Vos Post (jvospost3(AT)gmail.com), Jan 07 2005
|
|
|
FORMULA
| a(n) = A062301(n+1) = 1 - A100810(n).
|
|
|
MATHEMATICA
| Table[If[Prime[n] + 2 == Prime[n + 1], 1, 0], {n, 120}] (Ray Chandler)
|
|
|
CROSSREFS
| Sequence in context: A129950 A010051 A131929 * A139689 A073070 A099104
Adjacent sequences: A100818 A100819 A100820 * A100822 A100823 A100824
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Jan 06 2005
|
|
|
EXTENSIONS
| Corrected and extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 09 2005
|
| |
|
|
