|
Search: id:A166237
|
|
|
| A166237 |
|
Differences between consecutive products of two distinct primes. |
|
+0
1
|
|
| 4, 4, 1, 6, 1, 4, 7, 1, 1, 3, 1, 7, 5, 4, 2, 1, 4, 3, 4, 5, 3, 5, 3, 1, 1, 4, 2, 1, 1, 11, 5, 4, 3, 1, 3, 1, 6, 4, 1, 7, 1, 1, 2, 1, 9, 3, 1, 2, 5, 11, 1, 5, 2, 2, 7, 7, 1, 1, 2, 1, 3, 4, 1, 1, 2, 1, 1, 2, 5, 9, 2, 10, 2, 4, 1, 5, 3, 3, 2, 7, 4, 9, 4, 4, 3, 1, 2, 1, 1, 2, 4, 5, 5, 2, 2, 3, 1, 2, 5, 1, 4, 2, 5, 9, 3
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
a(n) = A006881(n+1)-A006881(n).
|
|
MATHEMATICA
|
f[n_]:=Last/@FactorInteger[n]=={1, 1}; a=6; lst={}; Do[If[f[n], AppendTo[lst, n-a]; a=n], {n, 9, 6!}]; lst
|
|
PROGRAM
|
(PARI) {m=106; v=vector(m); n=0; c=0; while(c<m, n++; if(bigomega(n)==2&&omega(n)==2, c++; v[c]=n)); w=vector(m-1, j, v[j+1]-v[j])} [From Klaus Brockhaus, Oct 13 2009]
(MAGMA) T:=[ n: n in [1..360] | #PrimeDivisors(n) eq 2 and &*[ d[2]: d in Factorization(n) ] eq 1 ]; [ T[j+1]-T[j]: j in [1..#T-1] ]; [From Klaus Brockhaus, Oct 13 2009]
|
|
CROSSREFS
|
Cf. A006881 (products of two distinct primes), A001358 (semiprimes: products of two primes), A065516 (differences between products of two primes), A001223 (differences between consecutive primes).
Sequence in context: A106642 A135012 A156380 this_sequence A021878 A016495 A047213
Adjacent sequences: A166234 A166235 A166236 this_sequence A166238 A166239 A166240
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Vladimir Orlovsky (4vladimir(AT)gmail.com), Oct 09 2009
|
|
EXTENSIONS
|
Edited by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Oct 13 2009
|
|
|
Search completed in 0.002 seconds
|
