A283332 a(n) = (Sum_{j=1..(K-1)/2} a(n-2*j+1)*a(n-2*j))/a(n-K) with a(1),...,a(K)=1, where K=9.

1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 7, 31, 223, 6943, 1548511, 10751318815, 16648535451082975, 178993712437422911994993439, 744995791758846743179449146618806505170999, 19049937502453316579424394593659892304405504872785268490952081866996

Offset

1,10

Links

Seiichi Manyama, Table of n, a(n) for n = 1..25

Matthew Christopher Russell, Using experimental mathematics to conjecture and prove theorems in the theory of partitions and commutative and non-commutative recurrences, PhD Dissertation, Mathematics Department, Rutgers University, May 2016.

Mathematica

a[n_]:=If[n<10, 1, Sum[a[n - 2j + 1]*a[n - 2j], {j, 4}]/a[n - 9]]; Table[a[n], {n, 1, 20}] (* Indranil Ghosh, Mar 18 2017 *)

Prog

(PARI) a(n)= if(n<10, 1, sum(j=1, 4, a(n - 2*j + 1)*a(n - 2*j))/a(n - 9));
for(n=1, 20, print1(a(n), ", ")) \\ Indranil Ghosh, Mar 18 2017

Crossrefs

Sequence in context: A359706 A156228 A218959 * A000289 A241426 A271676

Adjacent sequences: A283329 A283330 A283331 * A283333 A283334 A283335

Keyword

nonn

Author

N. J. A. Sloane, Mar 17 2017

Extensions

More terms from Seiichi Manyama, Mar 17 2017

Status

approved