A271949 Somos's sequence {b(4,n)} defined in comment in A078495: a(0)=a(1)=...=a(10)=1; for n>=11, a(n)=(a(n-1)*a(n-10)+a(n-5)*a(n-6))/a(n-11).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 8, 14, 26, 46, 76, 200, 356, 596, 1044, 1952, 5136, 17888, 48376, 109520, 225248, 724672, 1749280, 5359328, 18277312, 57803136, 235710976, 1067767168, 3411743616, 9748806656, 29696723456, 156028988416

Offset

0,12

Links

Seiichi Manyama, Table of n, a(n) for n = 0..343

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];
Map[a[4, #]&, Range[0, 50]] (* Peter J. C. Moses, Apr 17 2016 *)
RecurrenceTable[{Table[a[d]==1, {d, 0, 10}], a[n]==(a[n-1]a[n-10]+ a[n-5]a[n-6])/ a[n-11]}, a, {n, 50}] (* Harvey P. Dale, Oct 18 2021 *)

Prog

(PARI) {a(n) = if(n< 11, 1, (a(n-1)*a(n-10) + a(n-5)*a(n-6))/a(n-11))};
for(n=0, 30, print1(a(n), ", ")) \\ G. C. Greubel, Feb 21 2018
(Magma) [n le 11 select 1 else (Self(n-1)*Self(n-10) + Self(n-5)*Self(n- 6))/Self(n-11): n in [1..30]]; // G. C. Greubel, Feb 21 2018

Crossrefs

Cf. A006721, A078495, A268199, A271948.

Sequence in context: A352821 A102516 A156981 * A039089 A044956 A297139

Adjacent sequences: A271946 A271947 A271948 * A271950 A271951 A271952

Keyword

nonn

Author

Vladimir Shevelev and Peter J. C. Moses, Apr 17 2016

Status

approved