|
|
A268199
|
|
Somos's sequence {b(3,n)} defined in comment in A078495: a(0)=a(1)=...=a(8)=1; for n>=9, a(n)=(a(n-1)*a(n-8)+a(n-4)*a(n-5))/a(n-9).
|
|
7
|
|
|
1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 7, 13, 25, 45, 125, 233, 419, 805, 2252, 8343, 23554, 55889, 195533, 514781, 1769117, 6540689, 31873013, 162776741, 568710437, 1840702289, 10169970946, 53308101423, 363030298268, 1933899726085, 12286029791291
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,10
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
a[k_, n_]:=a[k, n]=If[n>2k+2, (a[k, (n-1)]*a[k, (n-2k-2)]+a[k, (n-k-1)]*a[k, (n-k-2)])/a[k, (n-2k-3)], 1];
a[ n_] := a[n] = Which[ n<0, a[8-n], n<9, 1, True, (a[n - 1] a[n - 8] + a[n - 4] a[n - 5]) / a[n - 9]]; (* Michael Somos, Nov 16 2016 *)
|
|
PROG
|
(PARI) {a(n) = if(n<= 8, 1, (a(n-1)*a(n-8)+a(n-4)*a(n-5))/a(n-9))};
(Magma) [n le 9 select 1 else (Self(n-1)*Self(n-8) + Self(n-4)*Self(n-5)) /Self(n-9): n in [1..40]]; // G. C. Greubel, Feb 21 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|