A271954 Somos's sequence {b(7,n)} defined in comment in A078495: a(0)=a(1)=...=a(16)=1; for n>=17, a(n)=(a(n-1)*a(n-16)+a(n-8)*a(n-9))/a(n-17).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 17, 29, 49, 79, 121, 177, 249, 597, 989, 1483, 2209, 3425, 5589, 9447, 16137, 36240, 109683, 273382, 574885, 1081260, 1898415, 3213378, 5381793, 15251949, 31924773, 78189885

Offset

0,18

Links

Seiichi Manyama, Table of n, a(n) for n = 0..487

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[7, #]&, Range[0, 50]] (* Peter J. C. Moses, Apr 17 2016 *)

Prog

(PARI) {a(n) = if(n<= 17, 1, (a(n-1)*a(n-16) + a(n-8)*a(n-9))/a(n-17))}; for(n=1, 50, print1(a(n), ", ")) \\ G. C. Greubel, Jul 30 2018
(Magma) [n le 17 select 1 else (Self(n-1)*Self(n-16)+Self(n-8)*Self(n-9))/Self(n-17): n in [1..60]]; // G. C. Greubel, Jul 30 2018

Crossrefs

Cf. A006721, A078495, A268199, A271948, A271949, A271950, A271952.

Sequence in context: A265730 A304248 A147591 * A330969 A033074 A067451

Adjacent sequences: A271951 A271952 A271953 * A271955 A271956 A271957

Keyword

nonn

Author

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

Status

approved