|
Search: id:A075832
|
|
|
| A075832 |
|
Let u(1) = u(2) = u(3) = u(4) = 1, u(n+4)*(n+4) = u(n+3)*(n+3)+u(n+2)*(n+2)+u(n+1)*(n+1)+u(n)*n; sequence gives values of n such that u(n) is an integer. |
|
+0
1
|
|
| 1, 2, 3, 4, 5, 67, 150, 154, 387, 547, 813, 1034, 1710, 4994, 13582, 700427, 1598953, 2960411
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
No more terms up to n=15*10^6. - Lambert Klasen (Lambert.Klasen(AT)gmx.net) and Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 05 2005
|
|
MATHEMATICA
|
a = {0, 1, 1, 1, 1}; Do[a = Rest[ Join[a, {((n - 4)a[[2]] + (n - 3)a[[3]] + (n - 2)a[[4]] + (n - 1)a[[5]])/n}]]; If[ IntegerQ[ Last[ a]], Print[n]], {n, 5, 2*10^6}] (* Robert G. Wilson v *)
|
|
PROGRAM
|
v = [1, 1, 1, 1]; for(k=0, 15, s=k*10^6+1; e=(k+1)*10^6; if(s==1, s=5); print(s, " - ", e, ":"); for(n=s, e, v[(n-1)%4+1]=((n-4)*v[(n-1)%4+1]+(n-3)*v[(n)%4+1]+(n-2)*v[(n+1)%4+1]+(n-1)*v[(n+\ 2)%4+1])/n; if(denominator(v[(n-1)%4+1])==1, print1(n, ", "))); print()) (Klasen)
|
|
CROSSREFS
|
Cf. A075770.
Sequence in context: A069881 A004856 A037327 this_sequence A037434 A033170 A097931
Adjacent sequences: A075829 A075830 A075831 this_sequence A075833 A075834 A075835
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Benoit Cloitre (benoit7848c(AT)orange.fr), Oct 14 2002
|
|
EXTENSIONS
|
Corrected and extended by Lambert Klasen (Lambert.Klasen(AT)gmx.net) and Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 05 2005
|
|
|
Search completed in 0.002 seconds
|
